Can't ssh or access via luci ASUS RT-AC57U after install

Hello

I followed the instructions on this page https://openwrt.org/toh/asus/rt-ac57u
As there were no install file, I used the upgrade file.
Restarted the router after install

Now unable to access http://192.168.1.1/cgi-bin/luci/mini/system/upgrade/ or ssh into the router.

The modem sees the router and it seems to be connected

Did i brick it by using the upgrade file? What other diagnostics can i do to help me figure the next steps?

Thanks in advance

What is the exact filename of the firmware image you used?

Have you tried pinging the router (192.168.1.1)? If that works, your device is probably booted and we can go from there.

used this: https://downloads.openwrt.org/releases/21.02.1/targets/ramips/mt7621/openwrt-21.02.1-ramips-mt7621-asus_rt-ac57u-squashfs-sysupgrade.bin

pings timeout

You aren't really specific from what you upgraded either (18.07.x, 19.07.x, 21.02.0 or OEM), but if I had to guess -especially considering the mt7621 target-, I'd put my money on an 19.07.x (or earlier) to 21.02.x upgrade, which means migrating to DSA (there should have been a huge warning message with further details). To cut the story short, and before going into further details at this point - give https://openwrt.org/docs/guide-user/troubleshooting/failsafe_and_factory_reset a try, in the form of letting your router fully boot up (wait at least 2 minutes after powering up, better 3-4 minutes to be on the extra safe side), press the reset button for over 10s (again, a little longer -like 20s- won't hurt) - leave the router alone for at least 5 minutes and check if you can get access again (first via your browser, if that fails via ssh).

thank you, there were no prior openwrt installs on this router
there were no error messages after mtd-write

Try doing the TFTP recovery, from the link you previously posted.

Performed failsafe reset and after 5 mins nmap 192.168.1.1 stated that the host is down
however -Pn shows that the host is up

Starting Nmap 7.92 ( https://nmap.org ) at 2022-01-23 15:05 UTC
Nmap scan report for ASUS_router (192.168.1.1)
Host is up (0.072s latency).
All 1000 scanned ports on ASUS_router (192.168.1.1) are in ignored states.
Not shown: 990 filtered tcp ports (no-response), 10 filtered tcp ports (host-unreach)
Nmap done: 1 IP address (1 host up) scanned in 5.92 seconds

Still unable to ssh, ping times out

trying TFTP next