You must take the boot.bin from the firmware version that's currently loaded to the device, renamed Ldr.bin and make update.txt file as per post #44 for inclusion in "Garmin/Updater/xxxx" where xxxx is appropriate HWID number. But i don't understand why you mention the proposed HWID folder name as "1947". That's for C4 chip version of nuvi 25x9 series. DriveSmart 40/50 is HWID 2267 therefore "Garmin/Updater/2267". You need to be absolutely sure which fw is currently flashed to the device as well as its actual HWID.