Power Button of One Plus Two Stopped working

Power Button of my One Plus Two ( Android Version 6.0.1,OS Version 3.6.1 ), suddenly stopped working. When I switch off Power Button , it shows Red power Button and Green Reboot Button. I press Red Power Button,it switchis off for a fraction of second and again switches on, on its own.Please guide me to solve this problem.
Thank you
ashokad71

Can you force a shutdown by pressing and holding Power for about 20 seconds, or does it still immediately power back on?

I tried the same but of no use.Also I deleted the Cache by Rebooting to safe Mode. That also did not helped.
Pl.advise.

I'd suspect a faulty button. Bring it to a repair shop.

Thanks. After the recent situation is over ,I will do that.
Take Care and stay safe.