Troubleshoot Seventeen Faulty Vape Devices

My collection of personal vapour devices has gradually stopped performing: the LED still lights up, yet no vapour is produced. I have already swapped in fresh batteries, brand-new coils/atomizers, and even replacement circuit boards, so the usual quick fixes are exhausted. I need an electronics-savvy troubleshooter who understands vape mods, pens, and similar hardware to fix these. I have about seventeen of these. They're first generation, three-part, meaning the atomizer is separate from the battery section. I've replaced the batteries, and the circuit boards. The batteries are working, as the LED is lighting when "drawn" on, but they're producing no vapour. I want to save these because I can't find them anymore, and it's the only kind I can use. I hope someone can help.