Just to clarify, if Andy's phone died in the same fashion as my S6 (and many others according to an online search), it went as follows.
In my case, the phone was working perfectly and the battery was running at around 65%. I like it to be on 100% at the start of the next day so I put it on charge via the plug in charger that comes with the phone. It beeps as normal and the charging light was flashing. Some time later I picked it up and the screen was blank. I pressed the power button, but nothing happened. I plugged it back in to the charger and no lights came on, it was dead. The same with the car wireless charger. I googled all of the fixes, press and hold power button and - volume, press and hold power button while holding the -volume and the home button but still nothing. I even tried all of the above whilst standing on one leg and whistling Dixie.
I've had several iPhones apart for various reasons, new screens, batteries etc. but Samsung just love to make you unglue the back case to get at the screws for the front case. iPhones are easy to work on by comparison. I've watched the videos on YouTube on how to bring them back to life but Samsung make it such a faff just to get at something simple.