Quote Originally Posted by zaicopx View Post
What's the use of this? My Garmin nuvi 65lm is currently still on software v.4.50, will running that bring my Garmin to very early firmware?
No it will UPDATE it to V5.60. It will also delete an onboard gupdate.gcd if present and dump a copy of the device's non-vol memory region as 154.bin (which you should keep a copy of, because it might save your device in the future).

Oh yeah, my Garmin can't enter preboot mode, ....
Yes it can and you've confirmed that by the rest of your statement :

..... I've tried it and it only goes into calibration mode.
I tried the preboot mode method and nothing like "software loading" etc. appeared, it just said garmin and entered calibration
The device can ONLY enter the white calibration screen AFTER it's been in preboot mode. If there's no flash initiated in the allotted time for preboot to be held, it will then show that screen. After re-calibration it will unilaterally reboot (or try to if it's soft-bricked).

More recent devices such as your nuvi 65 are more difficult to flash in preboot because the time spent in that mode is so brief and sometimes even hard to attain initially. Hence a bricked device is easier to flash via SD card if it sill manages to read from it (many bricked devices can't use an SD, depending on why they can't start).

You can confirm it's in preboot by having Windows Device Manager open and you'll see the list populated with GARMIN Devices when it's recognised by the PC. That's when it's in preboot and flashable with Updater.exe but if no flash is initiated, it will drop out and go to the white screen. You must be very quick to flash it that way.

From your additional information it's clear that it CAN enter preboot, but if it's not being seen in Device Manager as said above and you've properly reflowed the USB socket connections then it has some other hardware fault.

Please advise if your device still "bootlooping" like you said in initial post, and if so have you ejected the SD card with Garmin\gupdate.gcd on it?