Cmos.... or bios

i’ve been out of the pc fixing game for a while… so i gotta relearn some stuff… a friends computer won’t start up… nothing happens… earlier… i guess a power surge messed up the computer and reset the cmos settings… i fixed that… then they mentioned that the system clock is slow… its been a few weeks… but now the computer won’t start… they have and old built pc… so replacing the bios chip is a no go… but the cmos battery might work…

my question is… will a dead cmos battery prevent the pc from starting? i used to know… but like i said… been out the game for a while… and i’m in stupid mode