Hi, you’ll have to dig a bit, but there is quite a bit of information in this thread about people having difficulty upgrading and you may find the information that you’re looking for.
There are also a lot of standalone topics in the search, unfortunately I don’t know anything about the RYTM upgrade requirement between 1.50A and 1.71, but you can always contact elektron via the contact form in your account on elektron.se.
Good luck.