iPhone 6 very hot and battery drain

Hi all,

I realise that this is a fairly common complaint but having reviewed solutions many previous posts I've been unable to find a relevant solution.

In summary, I have an iPhone 6, 64GB running iOS 11.4.1. The problem is that when in standby the phone gets ridiculously (burning) hot in a very localised spot to the right of the home button, directly above the speaker outlet. All apps are closed. When I begin using the phone the heat dissipates and all works fine. However, as soon as the screen is locked again the heat returns. Touch ID does not work on this phone but the home button otherwise works perfectly. The phone does not get hot whilst it's charging. Also, the aforementioned spot does not get hot if the phone is otherwise generating 'normal' heat due to regular processing demands. Unsurprisingly, the battery drains pretty quickly.

I have reset the phone numerous times, restored to various back-up versions and also set the phone up as a new device. The hotspot problem has persisted throughout all scenarios.

So, any suggestions? Could anybody tell me which component lies immediately to the right of the home button? Any insights would be much appreciated.

Thanks