ZTE MF286D constant blue lights after snapshot upload

I built a snapshot firmware and added a few extra modules to customize it. After firmware upload the router didn't reappear as 192.168.1.1 and I've been unable to connect. Is this bricked and if so how do I recover it?

as far as I remember, MF286D install requires serial, simply use serial again, to recover.

I haven't used serial and installed OpenWRT firmware using framework software. I don't want to dismantle hardware or bother with soldering so if that's mandatory I'd rather just throw the modem in the bin and buy a different one. Is there a software only method of recovery?

Don't really need to solder, but keep the three wires connected to the PCB for 30 seconds, long enough to boot the initramfs - https://openwrt.org/toh/zte/mf286d#install_instructions.

I'm sure people will be happy to take it off your hands, if you give it away for free.

Not what I'm aware of.

You could however try failsafe mode - https://openwrt.org/docs/guide-user/troubleshooting/failsafe_and_factory_reset.

The power, 3G/4G and SIG lights are constant blue and with no blinking on any of them, so my attempts at triggering fail-safe mode were unsuccessful.
I'm going to look into a USB to TTF cable but what puts me off is that I found the packages side of OpenWRT to be very flaky in conjunction with this modem. I just wanted to use USB storage as extroot, then use AdGuardHome and Unbound either natively or through Docker, but couldn't get them to work together. As I was only doing a simple upgrade when the modem froze, perhaps this hardware is what's flaky and I'd be better replacing it with a 5G router instead?