Unbricking an UniElec U7621-06

For Developers
1

I was trying to flash a new firmware on a U7621-06, but I accidentally wiped the u-boot partition. Which methods can I use to restore the u-boot? Do I need JTAG?

2

if uboot's gone, you'll need JTAG.

3

I have little experience with it. Do I need a specific JTAG connector for these devices?

4

Here are openocd scripts and instructions specific for mt7622 with a mt7621 config file on directory up

I dont know if this will work for mt7621

Here some mt7621 related JTAG notes from the vonger.cn

http://vonger.cn/?m=202001

and

some more notes (use google translate to get it to english)
https://www.right.com.cn/forum/thread-266077-1-1.html