I think you are in India. Is that correct? If so, you need to get parts from Denon or their authorized service center. With receivers after a major repair, there are normally codes to enter and BIOS to re-flash. Repair is not like it used to be. You can fix a board and it still won't work because of software issues. From what you describe you need an authorized service center.
Surge protectors help protect from surges whatever the cause. Since you live in India if you own the kind of equipment you do, surge protection is mandatory not optional. If you had had surge protection in your home, almost certainly you would still have a working receiver.
I have done a careful parts search. The IC you listed is NOT available from any parts supplier. I suspect it was a specialized made to order chip for Denon.
I think you have ONLY two options.
1). Send it for repair to an authorized Denon service center.
2). Junk it and replace it. You may find the cost is similar.