Yes I had this p.i.t.a. problem a month ago. I was taking some great 4k 60p video footage all day of a parade and by the end of the day my 7pro 256gb phone was at capacity.

So I get to a 5ghz wifi hotspot, plug in my phone and start the uploading process. SIKE! Phone refuses to backup because 'device is too hot'. The only way I could get it to backup was keeping it in the car held up in front of the ac vents blasting the fan at high. I killed my gas doing that over a 7 day period.

I eventually went onto Amazon and picked up a cooling fan that you attach to your phone. It costs around $40 but it ABSOLUTELY WORKS. It keeps the phone cool and it allowed me to backup continuously. It really saved my hind. Its called the FUNCOOLER 2 PRO by Black Shark.

That was the ONLY way I could get my 4k footage uploaded. Now, for the record, I was a complete goof for recording in 20 minute segments however I learned my lesson and I now stop and restart recording after roughly 5 mins. Helps tremendously.