your next option would be to do a factory reset. this will determine if this is a software issue or not. keep in mind this will delete data, so backup accordingly. and do this from within your phone' settings. you can do a hard reset, but that will trip frp(factory reset protection) and you will need to know your google acct info or it will not let you proceed any further.
and if it still continues then you might want to look at warranty replacement options.