This is a replacement speed control card for a Hillbilly Compact Plus as pictured below.

The classic symtoms of an electric trolley that requires a new speed control unit are:

• The trolley will only go at one speed, usually full speed 
• The trolley is completely dead, and may emit a clicking noise

If the polarity has been reversed (ie a battery has been connected to the trolley 'red to black' and 'black to red') then 99% of the time this will damage the speed control card beyond repair.