I came to use my new Garmin the other day to find it completely flat, odd that the last time I used it & powered off it had >60% charge. Having since charged (which seems to take an absolute age), I’ve done a ride, powered off & the unit won’t now turn on? I’ve tried powering it via the wall & again nothing. It’s got a power symbol on the screen, but won’t do anything else. Has anyone else has this issue?