Error .. Unfortunately lgsetupwizard has stopped

[AC Question]

Dear Sirs,

LG Optimus L9 P768i

i have done a root for the phone and i have deleted some of the system files

1. HOME LG Launcher
2. LG keyboard

i have done a reset factory data for the phone

the phone has reboot normally to the setting pages

1. Choose Languae
2. Set connection by network data or wifi .. i SKIP
3. Back up date
4. the last page in the setp and i have PRESS DONE

Error .. unofrutnatly lgsetupwizard has stopped

the phone goes back to the first page of setting and not goes to into the phone main page

i assumed all this because of me deleting the files that i have mentioned

so i went to LG center to update the system

and i was told that the mainboard is broken and need to change ?!?!?!?!?!

i was shocked from the answer .. how can the mainboard broken and the phone can reboot

if the mainboard is broken the phone will hang on the LG LOGO and not continue

i was told to pay 6000 baht which is more expensive than buying a new phone

Please guide me how can i solve this problem