Appliance will not power on

I decided to take the mixer (Kenwood A701A) apart to clean it up properly. The entire machine was taken apart however, all the electronics and the engine was merely removed from the housing and not interfered with The same with the gearbox. Once everything had been cleaned, ( the gearbox and engine was left as it was) the mixer was assembled without any difficulties.

Once plugged in and switched on, no response from the engine. It was just completely dead.

What do I need to look for?