Need help  with this. Was working fine yesterday no changes

Since there is no led lights on the modem, I suggest you to try with different outlet with different power cord.

Also perform factory reset the modem and let us know if there is any changes in the behavior.

To perform factory reset, find the link given below:

http://arris.force.com/consumers/articles/General_FAQs/SB6190-Factory-Reset

After following the troubleshooting steps that been provided for “No LED lights” if the modem is still shows “Power on Failure” and as you had mentioned its been over 2 years than warranty claim might not be helpful as the warranty is only for 2 years span from the day of purchase .

It would be nice if you could share the Date of Purchase so we can check from our side ,  Also, if you want more information please contact arris.com/consumersupport.