Hi again and thanks for that information.
OK - you MAY want to replace the battery - with a new one. I have a link to a search I did (on Amazon) where you should be able to find one for a good price.
Click Here for Search Results --> http://amzn.to/2js9n9O
In the mean time, I would recommend CLEANING the contacts of the battery AND inside the device - with a bit of alcohol and a cotton swab (Q-tip).
Then reconnect to the charger and let it charge for AT LEAST 30 minutes, and then try to power it ON (to see if it comes ON).
If so, then turn the device OFF and reconnect to the charger for a few more hours - so that the battery has a chance to FULLY charge.
Since you found the cover LOOSE, I suspect that the battery may have come loose in your travels - OR - the battery MAY have started to "swell" - from the last time it was charged. Swelling is another sign of a battery "getting old & going bad" - and it should NOT be used at that point.
Please give these things a try and let me know your results.
Thanks, ***** *****
P.S. A sporting good store that carries GolfBuddy units (or proshop) MAY have replacement batteries too - but expect much higher prices than online.