Dear friend Kamelo,
Yes, disconnect the battery by removing the mobile body cover and then reconnect the battery.
You should buy a new mobile or get your old mobile repaired.
For we must all appear before the judgment seat of Christ, that each one may receive what is due him for the things done while in the body, whether good or bad. (Holy Bible 2 Corinthians 5:10)
By Him in Whose Hands my soul is, surely (Jesus,) the son of Mary will soon descend amongst you and will judge mankind justly (as a Just ruler);... Texts Bukhari Book #55, Hadith #657
God bless you in Christ Jesus mighty name.