Win7 boot issues with Precision 7710

As it says, my 7710 cannot boot from the m.2 512Gb 951NVMe SSD drive. It gives me a 0x0000098 error. I cannot repair it as my win7 install disc is telling me it is a different version of OS.

If I put it to legacy mode in bios and boot from the USB drive I made for installation of win7, with added drivers for USB 3.0 and the 951 NVMe , I can see all partitions, 5 of them, on my drive but I cannot install to the OS one, part 5, due to GPT.

If I change the setting to UEFI in bios and boot from the USB to start the install I only see partition 1. I am at loss here as all tutorial I read gives me suggestions I have already tried and that don't work.

I installed win10 on an old HDD and can run the laptop with it and I can see the OS drive with all files and access them just fine. I copied them to an external drive and few could not be copied due to restrictions but interestingly the transfer rate sometimes were down to few kb but mostly around 2-3mb/s.

I really would like to get my old install to work and backup files exist. Can I presume my SSD is shot and I should get a new one or is there a way out of the pickle I am in?

Thanks