Pachislo JPS 2027X code error

[Rage]

Hello
It's been a long time since I wrote (my machines are fine) but here I'm helping a friend.
His pachsilo is a 2008 model from JPS, the 2027X.
Recently, it rings at startup, with an error 5E and displays an error message (system error 1 apparently). He has already done a reset but on restarting, same problem. Does anyone know this error code? If so, what should be done?

Thanks
Regis (from France)