LS1 Ecu locked

Hi All , first of all I am pretty new to all this electronic tuning stuff but am certainly not new to modern cars or tuning in general.

We have just installed a new cam , lifters oil pump etc in a customers car Holden VX SS Auto, Using HP tuners I went to download the tune currently in the ecu and it wont let me in. Now the car had a otr and no maf so obviously it has been played with before. The current owner doesn't know who by or when.

Question is can I reflash the ecu using delcotds and my J Box back to the stock gm file and then have access to it to re do the mafless tune and tune to suit new setup, or are we just going to have to get another ecu and put in it.

I send lock ecu’s the Jsb in Melbourne he can unlock and reset to factory, I think it’s about $150 from memory and about a 5 day turn around depending on where you live.