F670Lv9.0 Telnet Access

Shared method does not work if you are on the latest Airtel firmware as it has been patched, i.e., 16B.
Tried on an older firmware; telnet works, but all commands have access denied, likely been rendered useless in the firm code itself.
has anyone had success logging into shell via UART?

i am stuck at username and password stage.

I don't have telegram; 12A is old unpatched firmware where a lot of things are unlocked regardless.
I reset the router with the older firmware, and it has been working; not much to do here tho TBH, but now it can be well-used with other ISPs.