Tenor Boot-up problem

Dear Forum members,
Can you please help me in the following issue:
I tried to upgrade the operating firmware on my unit (Tenor A800) and as a
matter
of fact the firmware file turned out to be corrupted or
something. As
a reason the unit is not starting up successfully now, instead
it just
writes
“Found file at 0x2830020
Executing file

…Unzip failed ”

And this messaage continues forever.
Can you please advise me how to get over this problem?
Your help is highly appreciated!

Kind Regards,