Quote Originally Posted by AlexWhiter View Post
I'd also recommend to backup the settings profile and all your tracks/points etc. to your computer - just to make sure you won't lose them during the firmware downgrade.
so I do, backing up my profile, more Settings.fit in directory Garmin\Settings and so i loose nothing, thanks for advice.
I start recordind track, remove one battery, replace it, restart gps and tracklog :
first- with fw 3.90 not patched : no problem
second- with patched 3.90+1 : no more problem
restoring previous profile and settings.fit, I only have to set gps+glonass and re-enable waas.

So no problem this time with not patched or patched firware !