Not all DIY builds work first time, but with a little patience and some investigation you may be able to debug your build yourself.
There is no silver bullet, it’s down to following a process with a good dollop of perseverance. It’s worthwhile exercising a little humility, and accepting that you may have made an error, rather than emailing FC to ask us why your build doesn’t work.

Here are the steps that you should take:

The vast majority of build issues are down to soldering inconsistencies. This is far more likely than a bad IC, for example. The first step of successful troubleshooting should always be to reflow all soldering to eliminate any dry joints (bad connections) or solder bridges (short circuits). This is also an opportunity to closely inspect your work – you might find some unsoldered pads, or an IC not inserted into its socket, for example. Next steps are to double check all resistor values are correct, and to check polarities of all diodes, transistors, ICs and electrolytic capacitors.