Nintendo switch black screen rabbit hole

Nintendo Questions Nintendo Switch
1

Hello,

I’ve come across another rabbit hole switch, The switch wont boot or display anything.
It is a v1 hac-cpu-20
I can successfully send a payload which turns the backlight on but does not display anything

Originally the board on its own would draw 0.07a constantly and successfully negotiates 15v
After I removed the nand and connected it back to the board it now draws 0.00a and occasionally jumps from 0.00a to 0.05a to 0.08a to 0.00a.
If i remove the nand the board draws a constant 0.07a to 0.08a

When powered with an original charger I get all the expected rails except the 0v8 cpu.
The max ic below the apu that should output the above rail does not seem to be enabled
It has the expected 4.2v and 1.8v readings on the nearby caps

Lastly everything on the board is clean and shows no sighs of being worked on,

I suspect this may have been a victim of a drop although the shell looks pristine

Additional information:

Rail → black on ground

0v8 CPU → 375 Ω
0v8 GPU → 51 Ω
1v1 → 1.18k Ω
1v8 → 5.08k Ω
1v15 → 40 Ω
1v35 → 600k / 3.6m Ω
3v3 → 178k Ω
5v → 3.3k Ω
Sys → ~670k Ω

If anyone has an idea or something obvious that I missed, please let me know!

Thanks

2

I should add that with a 5v usb connection to my pc, I get a constant 0.10a draw

3

Took another look at this switch today and was wondering since the switch accepts a payload (using rcm jig to get into rcm mode) and turns on the backlight, shouldn’t there be something displayed?
I looked over the lcd connector and it appears fine, the 8316 ic has both 1.8v enable signals and both +5v and -5v rails enabled
Also the nand has no issues initializing, tested it on another switch with hekate

4

I found one of the sub rails (LDO4 according to the max77620A) which has lower than expected resistance to ground (0.80k vs 3.7k on a working board)
This rail goes directly to the apu from the max77620 and does generate its expected 1.0v.
I’ll consider this a no fix due to the issue likely being the apu