Yes, I suggested to change it by 1. 5.01 would have been best if you had 5.00.
Still, no reason to panic (yet!) at this time. You need to find out how to put the 270 in pre-boot/service mode. It generally involved booting the unit with a finger somewhere or locking the unit with the power button and connecting the USB cable at the right time. Just start another post in the right Garmin section and ask how to do it. It may also be in the tutorial area here.
I never really paid attention on how to boot the GPS when there is a bad GCD on the flash, but it can be done. Maybe from the SD flash card or with a cure firmware. Again, there are people on this site that did it. We just need to get the information.