Don't work without Computer connection

Hello

I have a ALLBOT VR408 with an Arduino Mega 2560.
I took the Sketch from the Website and changed the Pin numbers.
Also i changed the shunts to Mega.

When im connected with the Computer, it works fine.
When i’m not connectet it looks like it has to less power.
I use 4 brand New alkaline AA Batteries, the Positive & Negativ Pol is correct.
The IR Smartphone APP also doesn’t work without the Computer connection.

Thank you for Helping