Usually there are no user serviceable parts when you see those odd shaped fasteners.
Were you able to remove the impeller and clean the parts and cavity? If so, reassemble the pump head and briefly plug it back in to see if the impeller spins.
Side note, if the filter is still under warranty, I wouldn't take apart anything that isn't listed as normal maintenance procedures.
Eheim Pimpette #270
Eheim Pro II 2028; Classics Series -2215, 2217, 2260, 2262; Pro 2229 Wet/Dry