At our school, we use +50 Latitude E5530 convertibles. We are facing a multitude of problems with these devices.

Some devices crash regularily with IRQ_LESS_OR_EQUAL BSOD.On one device, we performed a BIOS update to the recommended (by dell command update) version 1.14.3.  After the upgrade, windows keeps crashing permanently. Powering up the device is a game of luck. After that, the BIOS complains "timezone not set". When we enter the BIOS, no keyboard ore mouse are detected and not working!

After that, we tried the downgrade by pressing ESC+STRG, but that is not possible anymore! We managed to do the downgrade to 1.13 by restoring Windows but then Windows ist only starting normally once. After re-installing all drivers, the device can't be powered on anymore!

Other (still working) devices have problems with external 4k displays. When plugged in, the external monitor shows a picture, but the internal display gets black as soon as you select "mirrored screen". Only with extended screen the internal display is on. That is not usable at our school, since you cannot draw with the pen on the extended screen!

The next problem is with the use of our USB-C docking stations (LENOVO USB-C dock Gen3). The USB-C connector in den Insiprion E5530 sits quite deep in the case, so the USB-C-cable has to be plugged in very tight to get the display-lines connected (mostly). Also charging works not properly with the power-supply of the docking station. When the notebook is chared, the docking station can charge the device but when the battery is down, you have to use the original DELL power-supply to get the notebook startet. After that, it charges over the USB-dock! It won't start with any another brand usb-c power supply.