My wife's g4 got this problem yesterday. Verizon is sending us new phone. Problem can be temporarily remedied by placing the phone in the freezer so it doesn't heat up. Gives enough time to back up/fdr till it starts looping again.
I got the bootloop problem this past Monday. Contacted Verizon, they sent a G4 in the mail which is scheduled to arrive tomorrow.
Question: would it be wise to trade in the replacement G4 for something else like an HTC 10? Are the replacements likely to fail as well? Verizon currently gives $300 credit on a G4 trade-in.