Need to re-write U-boot from Pinephone pro currently in mass rom mode

[wolverine1]

Hi All;
I was trying to flash my emmc on Pinephone Pro and by mistake I erased instead my U-boot. I used an sd-card for the day and once the battery was drained the phone went into mass rom mode and I can no longer power it on.
After recharging the battery from a power station I tried to switch it on unsuccessfully. I tried as well the recovery mode (using the RE button on the back and it would work).
I can no longer see the device when running the lsblk command. However I see the rockship in mass rom mode when I run the lsusb command from my linux labtop.

I read few instruction and a script provided by the rkdeveloptool-master to flash the memory and see if I can copy across a new bin file (rk3399_loader_spinor_v1.15.114.bin) and from there being able to move out of the mass rom mode and use again the sd card. It was not successful.

I was wondering if there is U-boot image available that I can use and how can I copy it across to my phone memory since I am still on mass rom mode. I guess there are 2 questions in 1:
a) how to move out of the mass rom mode
b) How to reinstall the Uboot in my Pinephone Pro

Thank you.