Ok, since you say the device didnt get wet, nor was it dropped, and now it wont charge nor even turn on and a hard reset wont get it to flash anything on the screen.
Most likely the small battery cable slipped loose from the motherboard.. This can happen due to vibrations and bumps and jarring on your ride.. so lets watch this video.
You will see the exact battery cable and connector at 2 minutes 24 seconds. We need to diseemble the machine as sh own in that video and remove and reconnect that battery connector. I realize this may take you some time.
If you dont have the tiny screwdriver needed. Im not overly familiar with repair shops or stores in the UK but most electronics stores and some retail superstores should carry the tiny screwdriver sets for electronic repairs.. They usually cost less then 10$ US over here. But you will need a tiny screwdriver to get the machine open to check this cable.
If you get st uck or have any questions let me know. And I fully expect that when you have the proper tools you will want to continue this conversation or at least let me know that this worked for you!
I will watch for your replies going forward.
Senior Technician and Network Switching Systems Operator / Maintainer.