820-00165 will not turn on from battery power

[laptopcity]

bit of an odd one which im sure im missing something but banging my head so thought id put it out there, 820-00165 will not power on with battery power, now its not the keyboard the laptop will switch on and off fine with the mains connected , will even run from the battery once on, will even charge the battery but if i disconnect the mains and shut down it wont power on again, now i do have 8v at C7116 "PPVBAT_G3H_CHGR_R and same at R7151 and R7152 also measure 2.2 and 0 ohms, ive changed U7100 just for the hell of it and no joy . What am i missing ?? any help would be great

 

[2informaticos]

"if i disconnect the mains and shut down it wont power on again"
Just to be sure, machine stays on if unplug charger, but doesn't turn on with battery alone?

 

[laptopcity]

yes you got it

 

[2informaticos]

Did you try another battery?
PRAM reset done?

Try pressing power button for 2-3s...

 

[laptopcity]

yes tried all of that :-( think im going mad

 

[2informaticos]

Check RTC signals on battery alone.

 

[laptopcity]

ok , dont know how this is possible but the problem was the trackpad cable in the end, very slight corrosion on the cable but why this stopped the laptop from turning on via battery power is a mystery