I am having the same issue. I bought a G1 from a guy on CL and it had this triangle/ exclamation point problem. I was able to get it out of this by holding down Home + Back for 25 seconds, then I rebooted the phone. This worked. I was able to use the phone for about 24 hours (albeit a little glitchy). When I hooked it up to my charger, I came back an hour later and it was back to the triangle/ exclamation point problem. And now nothing I try will ressurect it. It will go thru the motions of acting like it is wiping and restoring, but it always goes back to the triangle/ exclamation point. What can I do next? Is there any way on earth to reload everything from the bottom up?