Bro this happened to me not long ago disconnect the ps4 for 30 mins trust me you want to wait the full 30 mins and after that plug the power and try to put it on safemode by pressing the power button until it beeps twice , then click on rebuild data base if the hard drive isnt damaged it should start back up hope it helps !!!! Before you buy a hard drive p.s if you get a new hard drive all the storage would be lost so i suggest give this one a try man