Switch HAC-CPU-20 Boots to 2nd logo then black screen


I have a Nintendo Switch HAC-CPU-20 board, the problem is ith will not boot past the 2nd logo, it will ust hang on a black screen with backlight on. Very occasionally, it will get to the Joycon connect screen, and you can connect a joycon, but it will freeze/lockup in a few seconds, then after a 12second power button press its back to black screens.

There is no obvious damage to the board, and no shorts around the M92, BQ or P13.
It will only slow charge at 450mA and it doesnt appear to be recognised when plugged into a PC, TegraRcmGUI says it is NOT in RCM mode.


Given that it occasionally boots, I would bet on it being something with a dodgy solder ball under it.
Maybe try putting pressure on different chips while booting to see if it gets you to the joycon screen. the SoC would be the obvious choice to start with, though I guess RAM and EMMC might be good ones to try too.

I removed the shield for the soc and ram and pressed down on the soc with my finger while powering on the Switch and it did end up getting past the joycon screen and completed setup, and it is now at the home screen, i dont know how long it will stay like this, or if there is anything i can try to see if the error still persists

Ahha. Well, I would guess at this point that there is a loose solder joint under the SoC. The “permanent” solution in that case would be a re-flow, though that comes with its own risks of course.

ok, it seems stable at the moment, but you know it will porbably come back at some point if left alone, ill leave it on for while and see if theres any change.

i dont suppose you have a guide or advice on reflowing the soc?

many thanks

I have only done it once, and I think it went ok (my bluescreen went away, but the unit had other issues). So I am probably not the person to walk you through it, though I did have a thread somewhere here on my blue screen switch and others gave a lot of advice, so if you can find that it may help.

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www tronicsfixforum com

brilliant thanks, ill report back if theres any change in the Switch and if i decide to go ahead and reflow

It is still up and running and fully charged, ive not really put it to work with games etc,

i dont suppose there is any diagnostic/testing software you can run is there?

for now ive put 4 little peices of thermal pad on each corner of the soc, so when the shield is on, it is applying presure to the soc, ill see if it lasts