EZ FLASH OMEGA not working with GBA

Hi everyone.

I bought an EZ flash omega on eBay and it was delivered yesterday. It worked very well since I followed the instruction on the website. But my GBA was freeze when I was playing Fire Emblem. Now the flash cart does not work. No Nintendo logo showing on the boot screen with/without the sd card. I also tried to clean the pin connectors but nothing happens.

Should I ask for a refund? Are there any solutions to fix it?

Thanks a lot