DevTerm CM4 No Power

I received my kit a few days ago. Assembled it last night, carefully and very precisely. Was very careful when installing the display LCD (flexed the plastic support clips and body rather than the LCD module.) Got the 18650 batteries charged and installed today. Pressing the power button does nothing. Removed the casing, and tried again (with just batteries, with both batteries and USB-C Power, and with just USB-C power) but no luck. LED next to power button flashes VERY briefly upon press but then nothing.

From my EE days, this indicates something is shorted and is causing the power-regulation circuit to crowbar and shutdown. I’ve verified there’s nothing externally shorting (the heat-sink sheet and thermal pad on the CM4 module). I’ve also verified the CM4 module is correctly inserted into the CPI carrier module, and that the CPI module is fully seated into the CPI mainboard. Same results. Also disconnected the thermal printer module to make sure that wasn’t an issue. No change.

This is leaving me wondering if I’ve gotten a bad board (CM4, CM4/CPi carrier, or CPI Mainboard) and if there are any simple ways to test what is failing.

UPDATE: Found the issue upon further perusal of similar issues on the forum…CM4 module was inserted reversed. After reversing it back, and reassembling, the DevTerm booted and is working so far!

This might sound stupid but are the batteries facing the correct way?

Yes, double checked those.

However, despite all logic, I noticed a post by someone else about the CM4 module being in backwards resulting in the same behavior. I’d been very careful to follow the instruction/assembly manual VERY carefully, including the apparent orientation of the CM4 module in the CPI carrier. The manual is apparently very wrong in this regard. I carefully removed the CM4 module and reversed it. Re-assembled, and it powered on and booted up just fine.

ClockworkPi needs to update the manual for the CM4, as it doesn’t use the screws included in the kit, nor is the orientation of the CM4 module in the illustration correct (or at least, it is VERY misleading.) I’m just very glad that the CM4 module wasn’t damaged by being inserted backwards.

I’m up and running, the included SIM card OS is updating as I type.


Good I’m glad to hear it wasn’t hardware related. I’m sure raspberry pi though of it going in backwards and made sure all the power pins wouldn’t short anything.

I’m happy to say everything seems to be working fine now.

However, why Raspberry Pi thought making the connections on the compute modules symmetrical and reversible is beyond me. It would have been SO simple to simply offset one from the other (or make the connectors of different lengths) so that reversing it wouldn’t be possible. That’s just not good design or engineering.

1 Like

A simple notch/key on one of the connectors would have been all it took but I guess they thought of it. They just wanna make you sweat when you put it in backwards.

Happened the same to me, didn’t know which way to put it as it wasn’t 100% clear. What I ended doing was just finding the antena notch on the drawing, and facing it with that point.

1 Like