How to Flash OpenWrt to BT HomeHub 3.0A?

Hi

I have an old BT HH3 lying around and I would like to try and flash OpenWRT to it. I have purchased a USB to TTL CP2102 UART Module 5Pin Serial Convertor and some cable for soldering. Eventually I will be flashing the BT HH5 but would like to test the HH3 first.

I've had a look on the https://openwrt.ebilan.co.uk/viewforum.php?f=5 and I can't find any decent guides. They all briefly go over everything but send you off to different places and nothing is explained in simple terms.

I would like to do a full backup, gain access via the UBOOT bootloader?? and then flash OpenWrt.

I've unlocked my BT HH3 (well at least I think I have after following the instructions very carefully), though I didn't get any errors is there a way to check it's unlocked? After unlocking where do I start?

Could someone shed some light here please?

P.S If I actually successfully flash this router I will be making a COMPLETE guide so that others can achieve this a lot easier.

Many thanks

Will

Could it probably be similar to HH5A? You can easily find material for that one.

If it's different, then maybe it's best to just not spend much effort on it. HH5A is much more powerful and can easily be bought on ebay for less than 10 pounds.