15V/0.45 HAC-CPU-21, not booting

Hi guys,

Got one of those “half ampere of death switches” again and looking for any troubleshooting tips. Thanks!

  • Current draw 15V/0.45A
  • USB port is okay and diode values okay
  • Couldn’t find any shorts
  • Voltage lines seem to be fine, eg 1v8, 3v3, VBAT
  • CPU/GPU buck voltages are normal
  • eMMC seems to be fine (checked with another switch)
  • Installed modchip for hekate. Does not glitch, gives error code short,long,long
    *== No eMMC CMD1 request (poor wiring, or dead CPU)

haven’t replaced M92 or fuel gauge yet

Any troubleshooting tips or is it dead CPU?

0.45a draw with the board by it self with no battery?
Could also be a bad nand or a nand connection issue, you could try the nand module in another switch (unpatched, don’t attempt to boot into hos, just rcm then hekate

If you plug the switch into a pc with tegrarcmgui open does it pick it up in rcm mode?

Thanks! I have checked the NAND with another switch. For bad NAND the modchip will give different error code.

Surprise surprise. The culprit was faulty M92. I removed the M92 and could run Hekate. After installing the M92 the switch boots.