So my Levoit Core 400S has been great for almost two years now but yesterday it just died completely. I press the power button and literally nothing happens no lights no fan no sound at all. It is plugged into the same outlet as my lamp and the lamp works fine so power is getting to it. Already tried different outlets and different cables and still dead. The unit is way out of warranty now and I really do not want to trash it because these things are not cheap. I saw some YouTube videos about opening them up and checking the fuse or the power board. Has anyone actually repaired a Levoit themselves? Is it even worth trying or are the parts impossible to find? Any step by step guidance would be hugely appreciated before I give up and buy a new one thanks guys!
Happened to my Core 300 last winter. Turned out the little glass fuse on the power board blew. You have to unscrew the bottom plate (four screws under the rubber feet) then the fuse is right there near where the cord comes in. It is a 2A 250V fast blow glass fuse 5x20mm. Picked one up at autozone for two dollars soldered it in and the thing fired right back up. Been running another year now no issues.
Mine did the exact same thing after a power surge. The fuse was fine but the little rectifier diode next to it fried. If you have basic soldering skills you can replace it but honestly for twenty bucks more you can just buy a new power board on aliexpress just search Levoit Core power supply board and your model. Takes about ten minutes to swap and way easier than diagnosing every component.
Before you tear it apart try the hard reset that worked on three of my Levoit units over the years. Unplug it completely then hold down the power button for a full thirty seconds while it is unplugged. Plug it back in while still holding the button for another ten seconds. Sounds stupid but it resets the internal capacitor discharge and fixed the no power issue twice for me when everything else tested fine.
My LV-PUR131 stopped turning on and it was the touch panel ribbon cable that came loose. These things vibrate over time and the little connector works itself out. Open the unit remove the filter take off the back panel and you will see a flat ribbon cable going to the control board. Just unplug it clean the contacts with alcohol and push it back firmly. Saved me from buying a new purifier.
Not worth repairing if it is the main PCB in my experience. Happened to my VortexAir and Levoit wanted 120 dollars for a replacement board which is basically the price of a new unit on sale. Ended up just getting a new Core 400S during black friday and using the dead one for parts. The fan motor alone is worth something if you ever need it later.
For anyone with the Core 600S the no power issue is almost always the thermal fuse buried inside the motor winding. You have to completely disassemble the fan assembly to get to it and it is a pain. I did it once with a replacement thermal fuse from ebay but honestly never again. Took me three hours and lots of swearing. Just buy a new one at that point.
Quick tip that saved my sisters Levoit last month. The power button membrane itself can fail and it feels like it is clicking but no connection is made. You can bypass it temporarily by shorting the two pins on the board with a paperclip (look up your model schematic) but obviously not a permanent fix. At least confirms if the rest of the unit is good before you spend money on parts.
I repair these all the time on the side. Ninety percent of dead Levoit units are either the fuse rectifier or the 5V buck converter chip on the power board. If you can use a multimeter check for 5V at the test points near the ribbon cable. No 5V means power board is toast. Yes parts are available just message me I sell refurbished boards for half retail.
Just chiming in that the newer smart models have a tiny surface mount fuse that looks like a resistor. Super easy to miss if you are not looking for it. Desolder the old one put a new 3A SMD fuse and you are golden. Did three of them last year all working perfectly now.
Thanks everyone! The 30 second button hold while unplugged actually brought mine back to life somehow 
Guess it just needed a full capacitor discharge.
Update fuse was blown replaced it for three bucks and it is running again. You guys rock!
Ribbon cable trick worked for me too thank you so much