bizarre 62s power off problem

Sent my Garmin 62s to Garmin for a screen change. They sent me back a new device. I began to download my maps onto it and the computer suddenly stopped recognizing it. Garmin gave me some advice on how to get the device recognized again, but it was something that had never happened to the previous device and I was a bit concerned. Anyhow I put the device away and 4 days ago I arrived in Italy in the mountains and started using the device with the downloaded Garmin supplied map. Shock horror it keeps saying it has lost its power supply and would I like to continue on battery power, after which, irrespective of what I do, it switches off. This happens continuously, sometimes every minute, other times it might last 30 minutes. I have changed batteries and battery types to no avail, also did a reset. Three emails to Garmin and no response. Today I realized that at nights it stays on longer, as it also does in the early morning. Today at 6am it would last as long as 10 minutes before powering off, from 8am up to about 11am I was on a very cold glacier and the Garmin stayed on! When the sun became too intense and the temperature rose it started powering off. However, if I shoved it into the snow for 5 minutes then i could get it to work for hours afterwards. Later in the evening I found that when I left the backing plate off the Garmin worked ok. Definitely appears that the problem is temperature related. I am desperate as I changed the screen glass and brought the map especially for this trip of 14 days, off which I am now entering the 4th day. I am really starting to feel resentment against Garmin. Any help appreciated.

 

Thanks. Garmin emailed me today with various instructions to try out. If none of them work then I will follow your recommendation.

 

Followed Garmins instructions, checking the software which turned out to be ok. So that was followed by a reset and a one hour wait with the device out on the balcony. Did not solve the problem so I am now checking the temperature. I did have an initial look at the data that came up when pressing start and enter, found that "bmap chk" has "fail" next to it. Any idea what that means?

 

Yes I dd that, twice. Strange thing is that in both cases during the reset a message popped up saying "cannot unlock map" with the box marked "enter" for me to press. There is no other option but to press it if I want to continue. I thought a reset should have got rid of that.
Can rule out temperature, today it was working at 30 degrees centigrade for about 4 hours before it starting switching off.

 

Right, just been there, two maps are listed, both referred to as "not lockable" which makes no sense as an attempt at a reset comes up with the advice that a map cannot be unlocked.

 

The only map I loaded is the Treking Italy one, which I also have as a bakup on sim card. It has occurred to me that it was not temperature change that was shutting down the device but actual movement to different locations much as you describe. I tried to test this by removing the sim card but realized that the loaded map is still there. I can disable the loaded map which did not help so maybe that is not enough and it should come off completely. I cannot find an option on the Map Manager to remove it.

 

At last, Garmin said I should send it in for a replacement. In fact I had two different people from Garmin contacting me. They are sayinf EXACTLY the same things, cutting and pasting from a script. Freaking me out a bit. Wish I had not brought anything other than the cheapest most basic GPS from them.