This account has document from 2014, and you are trying to change the account on 2016. As you see the program log, program tries to read the BKPF and BSEG base line fiscal year is 2016, however if the program change these documents to open item the amount from previous fisca year causes the problem.
Yesterday ı faced this issue too. Program cannot determines the fiscal year and the document numbers are fiscal year based configuration, that's why we accept to use non-open item management for that account and create a new account to follow open item from now.
In my opinion do not waste your time anymore create a new account and use that instead.