Error "i30" means that water remains in base because leakage or overflow. In this case, in order to prevent flooding, drain pump running continuously.
When we talk about AEG dishwasher, drain pump works even the power is turned off (must be connected to the wall outlet, otherwise anti-flooding system will not work).
The noise what you heard during operation indicates that something is blocking the drain pump.
Remedy: you should first remove the water from the bottom of the dishwasher and determine leakage then check why the drain pump makes noise.

If you work around the dishwasher, you always take care that appliance must be disconnected from the power supply.

Good luck.
Dado