Help with Flashing display

OK, Here's the deal. I have this ongoing problem. I had a Pioneer stereo in my 96 Tahoe that was working fine until I gave someone a hotshot. After that the display would flash and the stero wouldn't come back on. I tried to change the head unit and got the same thing. I have tried different ways of hooking it up and still have the same problem. Could my battery have been damaged? The truck still starts up with one turn of the key.my dad has a shovel

A hotshot?  Is that like using jumper cables to start another vehicle?  If so, it is possible you have blown an internal fuse in the head unit, or otherwise damaged it due to a voltage spike when the other car started up.  Unfortunately, if this is what happened it is repair time for the Pioneer.

Yeah a hot shot is the jumper cable thing. I thought that I damaged the head unit. But I have now tried three head units and can't get any of  them to work. They all have the flashing display once I hook the power up. This is driving me mad.my dad has a shovel

Hey, that is actually good news because it means there is probably just a blown fuse somewhere in the truck and that your HU is OK.  Check your fuse panels, and if the ones for instruments and radio do not look blown, check them with a meter to me sure.  It could also be almost any fuse unfortunately, depending on where the head gets powered from...

sound like you got 12v constant, but not ignition, , or vise versa.   Have to tested the wires with a probe??

Yea, it could possibly be a bad ground, or even corroded ground cables at the battery.  More likely there's a bad fuse somewhere, though.  Good luck and I hope it warms up for you soon!