System stuck in a safe mode boot and shuts off

My system was working fine when I got it yesterday. Then it randomly went into safe mode next time I fired it up. I tried doing all the repairs Sony says on the site but it just kept going into safe mode. Now it goes into safe mode, runs for about a min then shuts off. I took it apart to find it's clean as a pin on the inside, cmos battery was missing and had a dry spot on the apu. I fixed the dry spot and cmos system still does same thing. I'm thinking bad power supply would I be correct?