Turns off halfway through startup sound
So I plug in the AC cord and diagnostic LED 1 comes on, I press the power button and I get the startup sound and LED 2, than 3 and about halfway though the startup sound it goes off and back to only LED 1 on.
Heres the long story: I opened it up after the blinky folder issue and determined that the SATA cable was bad, so I pulled the HD and put it in a lightening enclosure and at which point it would boot up and seemed to operate fine. Shortly after it began rebooting on its own every couple of minutes, I started to sift through the log files but was not able to get anything useful before it shut down. Other than pulling the monitor and hard drive I have not changed anything.
Any suggestions on what to troubleshoot from here?