Thread: Zumo 550 Need firmware advice

Hello all,
I am new to the forum, after reading
[Only registered and activated users can see links. ].
I decided to write asking for advice, here my problem.
I own and Zumo 550, and everything as usual was working fine, including battery.
However after the 4.90 upgrade, the zumo died, (I thought) , meaning will not star on battery power, I removed the battery and tried again, nothing. so I connected the zumo to the usb and voila, start as a mass storage device, I left it all night thinking the battery discharged, but next morning same issue will not start on battery alone. ( the minute before the update battery and everything was a ok), I connected the unit to the Motorcycle and the unit runs fine, however on settings and about the last firmware I have is 4.80?
I tried to do the update again even with the warning of the full battery, but since is not working not sure, after that when I restarted the unit using the cradle, I get a message that the update couldn't be installed, "file must be corrupted download the file again from the internet".
I tried to downgrade the firmware to see if the unit will work on battery only mode, and again same error message even trying to downgrade the firmware.
I was reading about the "cure" files, and wondering if you think this could work for my unit?
I downloaded all the files to perform the cure but I have a new problem, I can't get the unit to Pre-Boot-mode, since I can't have it run only in battery, must be connected to the cradle or, I have found an adapted for another device I have (tmobile old mda). that will start the unit as if it was connected to the motorcycle.
However, I did a hard reset, I can put the unit in Diagnose mode, but the soon I will disconnect the power will be turn off immediately, hence I can't enter pre-boot-mode in order to do a flash. any suggestions?
I thought about buying a new battery however looks very suspicious that the moment I did the upgrade the battery died? in the exact moment? and trying to save a buck here, I thought I will give the forum a chance to see if there is a way to try something.
things that work.
Unit work fine connected to the the motorcycle.
I can enter mass storage device connected to the computer ( hence I can put files or erase files from the unit)
Things that do not work>
battery do not work immediately after the 4.90 update( not idea if there is a way to test the battery if is faulty or is good) I had the battery removed and re inserted with no luck.
Can't flash firmware, neither downgrade or upgrade due to constant error message (file corrupted)
Would like:
to be able to turn the unit on battery power have the latest upgrades. Not to spend the 200 bucks garmin wants for a refurbished unit without trying something else first.
Thanks for your help and forgive my poor English I write with an accent
Thanks all
E