Roland XV-5080 Error: Flash verify

[wango]

Hello to all,

This is my first visit here and I hope that someone can help me.
I'm trying to bring my XV-5080 to life again after a 13 year break but apart from the first 2 welcome screens and
the "replace the battery", nothing is happening after powering up, the screen is empty and the box is dead silent.
So to begin with I changed the battery and the phrase "battery replacement" disappeared.Then I tried to go into test mode
using the sequence given by cosmicdreamer.be in his blog with no luck. After that I tried to install OS 1.3 and it looked like
I was lucky this time. I have no data card which is recommended by some to install the OS so I did it by means of the 32 midi files.
Well, up to number 16 all was fine but at the end of midi file 16 all the "part select" buttons started to flash with the "Error: Flash verify" on
the screen so impossible to finish the installation.
I really would appreciate If someone could tell me what to do from here or has any idea what I'm missing.

Thanks a lot for your time
Ab van Goor