Main Board Power Failure


I was testing a sonar using the TX and RX lines on the 50 pin connector. I enabled Serial in the raspberry pi config, and rebooted the pi after the prompt. I have not been able to reconnect since. The 3.3v led on the main board also does not light up. I connected the pi via USB C to see if the problem was fixed, ad while it did work, after unplugging none of the status lights turn on. After more testing, only the 24V main LED turns on and none of the status lights turn on. I suspect that the main board has failed, although I’m not sure how. Any help or insight would be appreciated.


Attached are two images. The first one is when the main power switch is turned on. After a few seconds, the 3.3v LED and 2 of the LEDs next to the status go out. The final result is the second picture (posted below).

Hello, sorry you are having troubles.

it came to our attention recently that the center standoff was being put in the chassis.
This is not a good thing because it leads to a short to components on the sonar board that are between the two closely spaced Sonar mini-boards.

That center standoff is only for use for when a lower board is loaded that is not the sonar board.
This is a problem we have to fix and also have to make much clearer on our page that discusses adding the Sonar board. I will update that page now.

How about for now you try this: Remove red cable from battery (always do this for any work on boards). Then unscrew and take out that tall standoff that is near the center of the magni chassis.

Notice that there is NO HOLE on the sonar board there and that that standoff shorts out parts on the sonar.

If you put things back together without that short from the standoff and there is still an issue we will get you fixed up so do not worry.

Again, sorry our instructions for the sonar board are lacking in explaining that center standoff is NOT to be used.

This page that documents mounting the camera and the Sonar board now has highlighted in red section with a very clear statement that only the 4 standoffs, 2 on each far side, are used for sonar board mounting.

Sorry for this problem we will now followup with production to fix this issue.

Here is just edited page with red highlight note to help avoid this issue.

Please tell us if there was permanant damage and we will get things fixed for you.

Additional note: Let us know if things got permanently broken. I am VERY curious if that standoff destroys things. That make it EXTREMELY URGENT to fix in production if it is from production.

What I am hoping is our onboard 5V regulator just went into ‘overcurrent protection’ from the short. If that is the case you will be fine after removing that standoff.


I removed the standoff, but the power is now going on and off from the raspberry pi. The two status lights are blinking as well as the 3v3v and the 702/703 lights on the top of the board.
Any idea of what I could do?

Update: When powering on the robot, only the 24V main LED turns on as shown below.

Ok. Thanks for trying. I have escalated this issue to our production staff.

Please send an email to with Attention to Mark

At this point I would guess there has been damage.
We will get you a replacement. Contact me on the support email so we can get your info.

Sorry this happened. We so far think it was a small number of units but sadly you had one.


Can we try a few other things please:

With red battery cable unplugged from the battery remove and look at the large automobile type fuse that is plugged into the lower central front of the MCB board? If it is not blown plug it back in and re-connect the red lead to the battery.

For the rest of these tests disconnect the large 50 pin ribbon cable that goes from the MCB board to the switch board in case the switch board itself is the only thing damaged. Leave it disconnected.

Verify with a voltmeter if you have one that the voltage across both batteries is still high such as 23Volts or more. If it is very low what you describe can happen. Perhaps batteries got low due to the shorting. If the batteries got very low try using your charger to get the batteries back up to a charged state. They are fully charged when the charger led goes back to green.

Next look at and verify the switch board (the little board with the two switches on it) is in fact pushed all the way down into the connector on the MCB board.

If these checks look ok, try to power up the Magni again with the switch board still not connected.

Thank you,

Hi Mark,

I have verified the voltage of the batteries and they are 11V and 9V respectively. I will charge them now and see if the voltage goes back to 23V.

I have disconnected the ribbon from the MCB to the sonar board, but I’m not sure I understand what you mean by

For the rest of these tests disconnect the large 50 pin ribbon cable that goes from the MCB board to the switch board in case the switch board itself is the only thing damaged. Leave it disconnected.

From what I can see, the ribbon is not connected to the switch board, as the switch board is connected directly to the MCB. The ribbon is located on the top of the board, while the switch is at the bottom left.

If these checks look ok, try to power up the Magni again with the switch board still not connected.

Again, I’m not sure how to power on the Magni without the switch board since it contains the black switch to turn on the board.

Thanks for your help.

I am sorry, I meant to say leave the Sonar board disconnected till we get Magni running.
Just have the 50 pin ribbon cable disconnected was my intent. Sorry.

Yes the switch board must be always fully connected.

If your batteries were a total of 20v that would explain nothing powering up earlier.

So have switch board fully plugged in and recharge batteries. A healthy set of two batteries should charge up to over 28 volts. With the Magni off and fully charged batteries the batteries should be over 25 volts and close to 26 volts.

After charging the batteries for a couple hours, the voltage has now dropped to 4V and 1V. I believe this is a core issue but I am not sure if it is a problem from the batteries or the charger.

After leaving the batteries connected without a charger, the voltage seems to increase very slowly.

That sounds very much like a charger issue. I have seen before with the charger that the 110V main input power line can appear to be plugged in but it has to be pushed hard into the charger or the charger just drains the battery.

Depending on your country, verify the power input voltage is set properly on your charger. Are you on a 110V power system?

The charger light will light even if no 110V power

Do you recall if the charger was plugged into the Magni when the extra standoff was shorting out?

I am now wondering if that shorted center pin also has the ability to damage the charger.

From contact with the factory I have found out that they ship 5 standoffs in a little bag because they want everyone to have an extra one. The problem is that is is all too easy for customers to think that they should screw in all 5 into the Magni because after all there is a screw hole in that center position.

We are going to have the factory put a sticker over that center standoff hole to avoid it’s usage. The assembly instructions already said just 4 standoffs but as I mentioned I made it very clear only yesterday the dangers of a standoff in that center position.

I have switched the red switch on the charger from 240V to 115V as I am based in the US.
The voltage is now 14V on each battery, and the robot starts up normally. I will do more testing for the rest of the day to make sure, but it looks promising.

Thanks Mark for your help! I will reply to this post if I find that the issue isn’t fixed.

So we have 2 things going on. The standoff was a real problem but in fact our ‘root cause’ here is that your battery was not charging at all due to the charger set incorrectly. The standoff just complicated the issue.

I am going to put a strong note to have users check their charger primary voltage setting and add a picture in more than one place because this happens every once in a while.

This is another step our factory is supposed to take care of but it would be a good idea for us to put more steps in place for users. I think there is a sheet in the robot that talks about this but I know how it is, people get excited and a great many people do not read things.

I feel we need a red sticker on the power supply itself that is obvious that tells users to verify the primary power setting before usage.

I strongly suggest you let your battery get a very long charge at this time. The battery is fully charged when the charger fan stops and the LED2 remains green.

To see how badly the battery was degraded let it remain on the charger while you mess with the robot today (so maybe put the robot up on wood blocks so wheels don’t touch floor) then you an play with it and watch wheels move and so on.

After a long charge with charger plugged in the total battery voltage will be above 27V so then if you disconnect the charger a healthy set of 2 batteries will sit around 25volts or more for total voltage for hours if the Magni is off. If voltage drops right after charger disconnect below 24V that indicates the batteries are not very healthy.

Also I think it would be safe to shutdown the robot then remove red battery cable and put back in the 50 pin sonar cable then plug back on battery red cable. You can check out the sonars and other parts of the robot on this page: