Can't install firmware, diag light on

[3DPotter]

Hello, looking for help with installing firmware from a corrupted state. I have many many Duet boards and I am going through the bad pile to try and bring some life back to them. Some of the resurrection attempts have been successful, but only about 40% get a new life.

Board 1 status and steps done to it:
Board unresponsive with USB connection. Diag light off.
Inserted reset jumper pin. Diag light comes on.
Connected with BOSSA on COM13.
Installed 2.05.1 firmware, left reset pin in, firmware says it installed successfully. Board showing up as Bossa Program Port.
Even if reset jumper is removed, Diag light now remains on.
Board still showing up as Board showing up as Bossa Program Port in YAT.
Repeating these steps and removing the reset jumper before flashing in BOSSA has no effect, diag light remains on no matter what, can not continue. Board remains as Bossa Program Port in device manager.

Board 2 status and steps done to it: (same as 1 except diag light was on before reset jumper).
Board unresponsive with USB connection. Diag light ON
Inserted reset jumper pin.
Connected with BOSSA on COM13.
Installed 2.05.1 firmware, left reset pin in, firmware says it installed successfully. Board showing up as Bossa Program Port.
Even if reset jumper is removed, Diag light remains on.
Board still showing up as Board showing up as Bossa Program Port in YAT.
Repeating these steps and removing the reset jumper before flashing in BOSSA has no effect, diag light remains on no matter what, can not continue. Board remains as Bossa Program Port in device manager.

Board 3 status and steps done to it:
Board unresponsive with USB connection. Diag light ON
Tapped jumper for just a moment, device now shows up in windows.
Connected with BOSSA on COM13.
Installed 2.05.1 firmware, left reset pin in, firmware says it installed successfully. Board showing up as Duet board 2.
Diag light is off.
Board working normally, success.

I have tried different firmware versions. I have tried SAMBA. I have tried from cmd (cmd does not work as it says the sectors are locked when i run it, as I have checked the lock button in BOSSA and SAMBA).
I have followed https://duet3d.dozuki.com/Wiki/Installing_and_Updating_Firmware
I have tried: https://forum.duet3d.com/topic/19054/duet-2-ethernet-no-connection
I was using this as a guide: https://youtu.be/UPu7_RPE1d0?t=263

SOME, but not all, of these boards are from 3rd party manufactures.

Some pictures: https://imgur.com/a/oIcF5IQ

[3DPotter]

@3dpotter

FOUND SOLUTION.

After connection is established in BOSSA, you then plug in the reset jumper for 1 second. And then push the update. Update installs normally, but then after board is rebooted, diag light is off and board shows up correctly in device manager/yat.

This means for unresponsive boards you have to leave the reset pin in until you can connect with BOSSA, and then take it out, reconnect/relaunch again, and then do the step I listed above. This just saved like 10+ boards. woot.