Check out this great article by GWJax on how to resolve issues with the IR LED and remote on your Roboquad! Here's a sample:

Now, let's check the LED to see if we are getting anything to it. In the photo below, you will see 3 pad in a sideways triangle, and it's located to the left of the blue component: "a 4Mhz crystal." The one you want is the one on the far left, which is in front of Q1's collector. Find the Black battery line and make note of where it is connected to the battery housing. Now, get out your meter and put the setting to 20v DC (or auto DC) depending on what kind of meter you have. Place the batteries inside the housing; make sure to remember where the black wire was connected. Place your black ground lead from your meter in between the battery and spring. Place the red lead from the meter on the test pad in front; For the Q1's collector, you should read almost 0V. Now, press a button, and the stop button and it should read about 0.35v or so - and then back to 0V. If this test works, then Q1 is working and the CPU is working. The IR LED is dead and should be replaced.

Read this detailed and helpful article here!

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