How to fix my Android Phone "Unfortunetly has stopped" (Alacatel One Touch Idol X)

Hi! I really need my mom's Android phone to be fixed. I am his son, and feeling upset. I borrow it from her everyday. So here is the problem, I FIRMWARE UPDATE it, and then the phone started to break. I CAN'T OPEN ANY APPS, it just says "Unfortunetly, [app name] has stopped" everytime I open any apps except Message, Browser or any basic app from a phone. I tried everything to remove it, from clearing app data to going in to the volume keys + home steps and etc. So I need my mom to forgive me. So I went to my neighbor (who knows a lot) to fix it. He said we need to reset the phone, and everything will be fixed. We reset it 2 times. And still nothing. He even connected this to his computer to check if there is a virus. I didn't knew the results. So, I am using that phone NOW. Quick recap, FIRMWARE UPDATED THE PHONE, "Unfortunetly has stopped", reseted the phone 2 times. So I need your help to fix my mom's phone. Respond for any steps on how to fix it. I want my mom to forgive me. HELP and peace.