Need help! My 14 yrold cousins FB has been hacked and his account now has stuff related to ISIS

Hey guys! I kinda need some help here… my 14 yr old cousins facebook account has probably been hacked. Someone logged in and deleted all of his older posts and posted ISIS links and changed his DP to the ISIS flag… So heres what happened…

He was playing PUBG using a VPN service and he gotta text on whatsapp asking for his login credentials in return for UC …UC are credits they use on PUBG to buy stuff in the game i guess… He basically said the only way to buy UC was to give him his gmail credentials… he did not and that was the end of the convo…

Last night while he was playing PUBG he gotta notification on his phone saying his PUBG account has been logged in on another device (he uses FB login to play PUBG)… He then tried to login to his FB (through the app) he noticed that his previous posts were deleted and stuff related to ISIS…he dint know what to do and logged out… when he tried to check after sometime he noticed that the account was locked i guess? Cuz he couldnt login… now when he tries to login with his password it says “To help us check that this account belongs to you, we need a photo of your official ID”… it looks like the account has been freezed cuz it doesnt turn up in search results so we cant report the account… his instagram also doesnt show up in search results since his instagram was also connected to his FB…

He had created his FB account using his phone number and not his email…
Should he be uploading his ID? …all he has is his school ID card…

Im not sure how this happened… the person who texted him - his number is now switched off… truecaller says its from UP (Uattar Pradesh, India)… Im not even sure if its related because his FB ID was created using his phone number alone… Please help!

ive got screenshots of the whatsaoo convo … should i post it here?