I think It’s just a resistor like those cream colored ones although I’ve never seen one with a V although that could be left over from the board designers, it’s found everywhere in eletronics and is used for power management.
Can you give any more details? check if there’s anything covering the top front grill or any gunk in it, check the microphone/call volume, try restarting the app using it via pressing the square next to the home botton and swiping it, maybe even searching the app in main settings and removing the cache (don’t worry it’s just tempory data), try restarting it device via the power button.
Check if that specific laptop (hopefully there’s a model number under it) has a port that outports a display and connect it to a tv or monitor to see if there’s any image, if so then it could be just the display needs replacing.
That is really odd, can you provide anymore info, otherwise I think you will need to either, use a different account, check the device is up to date, or go into the settings and factory reset it which if like other android versions will be around the bottom sections of the system settings. hopefully any of those will fix the issue.
Do you know what could have caused it? Unfortinately like buttons the D-pad is just a plastic cap connected to rubber that touches the circuit board so unless you got a decent repair shop nearby you would probably have to open it up and hope anything looks out of the ordinary.
As glass is obviously present your best bet is to use one of the guides to remove and reinsert the screen, which I believe is the first part to remove. If you’re not concerned how it looks then just ignore it the 6 or even 6s doesn’t have any water resistance anyway. If I were to guess the cause then it’s likely due to the bendgate issue those particularly with the plus varient suffered from at launch.