You don't need an account and you don't need to buy credits for repairing the EROM; it's free.
Use the Wotan client. Leave login and password blank.
WOTANSERVER, erom repair guide, dcu-60 db2020 phones only
a.Turn off the phone, remove the battery, sim and memory card,
1.download wotan
2.run wotan.exe
3.erase all log-in information
4.Press start button
5.Insert the battery then connect the phone while holding down 2+5
6.Release the buttons then wotan should update your erom.