Lenovo Thinkpad T410 no power

[kalilinux25]

1ST MOSFET Q9
source / drain- 98.2K
source / gate-141K
gate / drain- 412K

Q36
source / drain - 1.3M
source / gate- 947K
gate / drain-954K

remove U41 (tps51222) cool down the board for 5 mins . Check resistance to ground, red prove to gnd and lack probe to coil, L3- has 1.0k same , and L4- has 23.ohms.

[mon2]

Replace the first dcin mosfet.

[kalilinux25]

Replace the first dcin mosfet.

replaced with Si7121dn to TPCC8067-H MOSFET check gate to source -101k gate to drain 415k source to drain-185k still having 19v on gate but it pass the 19v now still unit doesn't have 5v as 3v I'll post the charger ic pin voltages

[kalilinux25]

replaced with Si7121dn to TPCC8067-H MOSFET check gate to source -101k gate to drain 415k source to drain-185k still having 19v on gate but it pass the 19v now still unit doesn't have 5v as 3v I'll post the charger ic pin voltages

1 - CE -0V 2 - ACN -18.69 3 - ACP-18.69 4 - LPMOD# -0V 5 - ACDET -2.5 6 - ACSET - 0V 7 - LPREF -0V 8 - TRICKL -0V 9 - AGND - 0V 10 - VREF -3.3V 11 - VADC -0V 12 - VADJ - 0V 13 - EXTPWR# -0V 14 - VDAC -1V 15 - FSET -0V 16 - IADAPT -0V 17 - ISET -0V 18 - BAT - 0V 19 - CSN - 20 - CSP - 21 - CELLS - 22 - DPMDET# 23 - PGND 24 - LODRV 25 - REGN - 0V 26 - SW 27 - HIDRV -0V 28 - BTST PAD - (Power GND – must be connected to board ground)

✅ 4. Injected 3.3V into VCC3M rail
Done using a lab power supply with current limit

✅ LPMOD# rose to 3.1V, indicating charger came out of sleep

CONFIRMED: Charger logic was blocked due to missing 3.3V

✅ 5. Checked REGN (pin 25)
Voltage: Still 0V ❌

Resistance to GND: 164kΩ → ✅ No short, load is normal

✅ REGN capacitor and components appear OK

❌ REGN internal LDO not turning on

EN pin (IS-PWRSHUTDOWN) = 0V → ❌ TPS51221 not generating VCC3M/VCC5M
BQ24741 is not generating REGN, even when all enable conditions are met

[mon2]

Si7121dn Was replaced with TPCC8067-H mosfet?

These are not the same type of mosfets.

Original is a P-channel type; replaced is N-channel type.

Enter the same details for advice on Grok while I work on my beauty sleep. I think chatgpt is making an error on this alternate mosfet.

Also confirm the pin voltage of pin 28 on the charger IC.

https://www.mouser.com/ds/2/408/TPCC...zIZffPzM_h0Nkw