help my RAZR XT910 is on Flash Failure

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Hello I have a problem with my Razr xt910 eu.FR
after a flash via fastboot I have left the black screen that says AP fastboot flash failure
If I put it in recovery and normal powerup select the phone and start working, but if I turn it off and try to turn the screen back I usually flash failure
how do I restore the normal situation
my phone has no root and has the original recovery
Help me
I also tried to give the command fastboot continue but I get the following result
FAILED resume booting <remote unsupported command>
with fastboot erase kpanic instead
C: \ Users \ android-sdk \ tools> fastboot erase kpanic
erasing 'kpanic' ...
(bootloader) Command restricted
FAILED (remote
finished. Total time: 0.010s

What do you recommend?
send it for repair?
the guarantee is no longer valid?

thanks