Every pre-soldered Zega Mame Gear is fully tested prior to shipping including all inputs, Audio (headphone and speaker), Video HDMI Out (if available) & Power supply. If you do encounter any issue DO NOT CHANGING SOFTWARE SETTINGS
If you find you are having to press hard to register an input I would recommend ensuring the board is not offset and cleaning all the buttons contacts and membranes with isopropyl alcohol. Sometimes a little more than a rub with alcohol may be needed. I prefer the lightly rub the area with scotchbrite prior to cleaning.
Your TV / Monitor may not be able to display the low default resolution if using an older pre-configured image. You can edit the boot/config.txt and increase the default resolution or try using the newest base image available through the Downloads area of the website
Please ensure the battery polarity is correct. Not all battery connectors are the same. Double check the ensure the red battery wire is going to the + pin on the Power Board
Ensure the volume wheel is turned all the way up. Ensure the audio connectors are both securely fitting into both the Audio Board and Mainboard
The next step would be to check and re-flow the LCD ribbon, however this can be tricky if you are not confident in your soldering ability. The LCD would need separating from the adhesive pads and lifted to gain access, and to re-flow, the ribbon cable. Attempting this yourself will void any warranty so please be 100% confident before trying.