From my experience, having had one S10+ power down at 85-90% battery after heating up abruptly while in my pocket (then never powering on again under any circumstances), the overheat condition is not caused by charging. Some heating while charging is not unusual...my S8+/S9+ would also warm up especially when fast charging, then cool back down once the charge surpassed 90%. The S10+ seems to do the same.
The problematic heating seems to occur when the S10+ is connected normally to a mobile LTE network. The rear-center of the device heats up (not hot to the touch but noticeably warm), and what will usually get it to cool back down is to quickly Optimize within Settings > Device care. Sometimes rebooting, powering on into Recovery mode and wiping the cache partition will also help stop the heating (during normal use of the S10+).
I've noticed that my replacement S10+ has run warm a few times while I was out and about connected to LTE, but it has cooled back down on its own after optimizing within Device care, and has not auto powered off (if that happens again, I'll probably be dealing with another dead S10+).
To all whom has received your phone back from Samsung service center, were your issues resolved?
My S10+ has been at the Samsung Service Center since last Friday (4/26.) Got a voice message today (5/1) asking me to elaborate more on my issues as they didn't find anything wrong based on initial testing. :^(
It's already disappointing enough that a new flagship phone has been plaguing with issues after issues for the past 2 months (since 3/7) and eventually having to send it in for a service, but learning that there will likely be nothing done to address the issues (bad LTE connections w/Sprint, heating up when making calls, battery draining, etc.) is leaving me a really bad taste with Samsung.
No problems the first two weeks, I recently turned on and made some Bixby Routines and now my phone won't get a full charge overnight & I wake up to it being extremely hot. This morning there was a temperature warning and it had stopped charging because of that. I have Mobile Hotspot, Data, Bluetooth & Always On display on. Wifi off and everything else as it. I've also been falling asleep with the Galaxy Buds streaming music. I turned off just Mobile Hotspot and it didn't help, I imagine turning off the whole routine would fix this but I shouldn't have to, am I overworking it or should it work?
Have you tried a different charger? Have you charged the device with multiple outlets? Does it allow you to reach a full charge when the device is placed into safe mode?
You can try these steps, your phone won't be wiped. Enter settings, then type reset into the bar. Do reset settings, accessibility, and network. Reboot afterwards.
Also, are you using a wireless charger without a fan? It produces more heat than wired.
this last Monday (4/29) I woke up and my Galaxy S10+ was extremely hot, right under the Bixby button and on the back in the same area. I haven't charged it overninght because it was charged the evening before. The one thing I noticed is my Watch Active died overnight (i thought it will last till the morning). I checked and there were no apps draining the battery, yet the phone was really hot. After I restarted the S10+ it cooled down and is still ok. At the time of restart I put my Watch Active on the charger (letting you know in case it matters, it was charging however it didn't power on). Today I noticed that the left side of the phone (that was hot) seems to be swollen a little compared to the right side that remained cool. Please see the attached photos. Hope it's not the Note 7 disaster all over again (this time without even charging). Anyway, this phone is not in its original state (pretty much the body is broken), please advise how to resolve the issue.
I can understand your concern, just send us a private message with your model code and IMEI number and we'll be happy to look into this for you.