Q: My imac 2006 shut off in a power surge and now it only starts to come on, then small white light blinks once and goes off

Take it to an Apple Store for diagnosis.

Understand that an Apple store may say they cannot look at it because they consider a 2006 iMac obsolete. "Looking at it" can vary from store to store but, as far as service/repair goes, I'm pretty sure none of them will fix it. Apple's article on the "supported/vintage/obsolete" issue with computers shows their policy:

Vintage and obsolete products - Apple Support