https://parkguell.barcelona/en
You can get there by e-bike, but once there you should walk it.
With Covid issue there are quite a few visiting restrictions now, you should check their website
I have a similar problem, sometimes when batter reaches 30% , motor does not assist. or if you are walking side by side with the bike, with the walking assist button pressed ( does not matter if battiery is whatever % full or empty) , motor does not assist. Normally, I just set off the system...