Review on Advanced Mapping Solutions with Southwire M400TP Professional Mapper by Louis Mechtak

This unit works very well but it locks if you aren't careful with the mode button. The problem seems to be software that isn't very tolerant of long button presses and can cause the device to get stuck in some weird modes. If you press the button briefly (1 second or less), the device enters mapping mode and works normally. Pressing the button again (long press) can lock the device. If it blocks, the battery must be removed to restart the device. If you follow the prompts to enter sound mode, it will work correctly as long as you press the keys very gently. For the default cable test feature, it's best to let the device turn off automatically rather than trying to turn it off with a long press. Update 11/15/20: My device has stopped working now and only flashes 4 and 8 when switched on. Replacing the batteries does not solve the problem. They asked for a replacement so we'll see what happens.