Just had a dreadful day when I thought my Pico 4424 was broken. I went out to do some work in an unheated environment and realized I had forgotten to take the supplied USB lead with me. So I found a 0.63m long one and plugged that in. With no BNC connector plugged in, the notional zero read +15mV on the -50 / +50mv range and 0.45v on the -2 / +2v range. Worse still when I tried to input a signal to the scope on -2 / +2v range, it refused to show values above 0.45v. (I confirmed this with voltmeter and a battery.) Thinking it might be condensation (the snow was crisp) I tried warming the Pico up but with no success. So came home and tried again on a range of USB leads. It appears that both a 06.3m and a 0.53m long USB lead cause the same problem even though they are OK for other uses. Other USB leads over 1m long were found OK. But the 0.53m plus a 2.5m USB extension lead was not OK. Has anyone an explanation for this observation? I must admit I am just grateful I only wasted 200 miles of driving and am not faced with a faulty Pico.