hey guys, i have a 820-00840 which im using 820-00875 as schematics and board view, Customer opened the laptop for some reason and shorted F4800 , replaced it and it worked fine, battery was showing X, so i thought maybe he just killed his battery, placed a Known working battery and still X, do you guys think it might just be a bad ISL? Computer seems to still run from battery when unplugged, just shows X , just asking before i try to order.