MT7621 - 21.02/Master feedback firmware image test - IPV6 offload and disabled Flow Control

Hello, need a little help.

I had a hootoo/strong 1200 device running openwrt.

I tried to create a patch for my device, edited the dts files, added the compatiblity for network etc.

After building i thought of flashing the initramfs image in order to "test" the firmware before running sysupgrade, thinking initramfs doesn't "write" anything on the device but i was wrong.

Unfortunately flashing the initramfs kernel on the device bricked it and i cannot connect to it via putty.

Does flashing initramfs image via openwrt can brick the device?

Any tips on recovering the device? do I need to connect to serial port?

Thanks,
St96