Hi Soetie and

to the forum.
I suspect the "Eb5" is just a visual notification that the
EBS is engaged due to a brake lever being stuck partially open, which can easily occur if you have plugged in the brake lever switch connector before the brake Bowden cables are physically connected to the levers and one of the levers is not fully released because the cable attachment pivot is preventing the lever from returning fully:

If the brake levers are definitely fully returned to the released position and you are still seeing the EbS notification, it could be due to a faulty brake switch or the wiring going to it.
Unplug both brake switch connectors and see if the EbS notification disappears. If it does, plug in the brake connectors one at a time to determine which one is causing the problem.
Alan