Automatic Robot Vacuum Cleaner

Unfortunately, I didn’t see all the “does not turn on” reviews until after I bought them. I bought four since they were so cheap and I wanted to have basic cleaning in different rooms. NONE OF THE FOUR TURNED ON. I followed all the same charging and reset steps that everyone else did to no avail. I went a little deeper and busted out my trusty voltmeter and measured the voltage at the power adapter and it was a solid 13V. Good. I measured the voltage of the battery and it was 0.03V. Bad. It should be around 11.1V after charging the whole night. I then checked the voltage at the 4 pin battery header on the unit side with the power adapter plugged in and it was showing around 0V between the red and black wires, 1.5V between the outer yellow and black wires and 0V between the inner yellow and black wires. With the battery and power adapter plugged in, I measured about 0.03V between the red and black wires. I’m thinking that on the defective units, the unit is not charging the batteries. How this gets past QA is beyond me. If I had the time to open one up, maybe I can figure out why it’s not working but I don’t have time that. It’s because I don’t have time that I bought FOUR vacuums! These are getting returned.