thank you very much for your question. My name is***** am a computer expert since 17 years and I will be assisting you today.
No worries, this can be fixed (had the same situation with another client already)! Can I remotely connect to your computer please, so that I can directly resolve the problem for you while you can relax and watch me doing it on your screen? This is an optional service with a one-time flat fee, regardless of how long it will take me to fix the problem. We can resume it at any time, without additional costs. It also is safe, as you will be watching your screen and we will chat there as well, so that you will always know what I will be doing next while fixing the problem.
Thanks for your patience and best regards,
Sorry to hear this, but you are talking with a independent computer expert here. You´ve asked your question at JustAnswer, which matches people with computer questions with computer experts all over the world and I was the one who got assigned to you today. However, I own both of these drives too (256GB one for the boot, 512GB one for data), so I know how to set these up. However, why are you re-installing Windows 10 right now if I may ask and to which of the both drives?
Should we want to remote-connect later on, the price for that is a flat fee of $39, regardless how long it takes me to fix the problem.