Hello,
I had the same problem and posted in the custom firmware forum, and I got a reply and the solution from developer pcristi.
I installed new 17.5.1 version from his link and everything is good again.
I installed very simple, with internal file manager from the downloaded kodi file on the internal HDD, not from USB drive. All settings were maintained.
I quote his post:
Kodi 17.5.1 include a fix of startup crash and is roll out on Google play soon will be available over automatic update, until then get it form Kodi mirror.
http://mirrors.kodi.tv/releases/android/arm/kodi-17.5.1-Krypton-armeabi-v7a.apk
More details about crash of Kodi 17.5 can be get it on Kodi 17.5 crash topic
http://www.futeko.com/newforum/index.php?topic=2487.0
Cheeers, everybody.