My undergraduate thesis project is a failure and I don't know what to do
&quot;It didn't work&quot; is not a thesis.
However, &quot;this is what I made, this is how I tested it, these are the results of those tests, this is how I attempted to fix/would attempt to fix in the future&quot;, etc, can be just fine, even if the ultimate conclusion is that your device isn't currently functional.
Undergraduate theses are typically fairly short-term projects, so you may not be able to follow up with all the avenues you would have for a longer project.
Most importantly, though, talk to your supervisor. Their role as a supervisor is for exactly the situation you're in: applying their experience and expertise as a researcher to help guide you in what to do. If everything worked out perfectly without any kinks or setbacks a supervisor would hardly be necessary.
Also most importantly (I'm running out of superlatives here), as a student, the success/failure of the endeavor should be primarily judged on what you as the student have learned along the way rather than the overall outcome (the proverbial &quot;it's the journey not the destination&quot;). Your device may not be working, but if you've learned something along the way I would not say the project is a &quot;failure&quot;.