Well, if rebooting doesn't help you can try to open your phone and reseat the LCD cable - as long your phone do not have any warranty anymore.

Hey! Shortly: This is the cell-antenna and you need to connect it on the board at this little round connector.

Hey! Do you see any diagnostic-LED on the front of your Optiplex? I mean the numbers 1-2-3-4. And does it show any reaction after you tried to turn it on?

Hey! Do you hear any beeps as you tried to start it? If yes, please check if you find your code here: https://support.apple.com/en-us/HT202768 and here: https://support.apple.com/en-us/HT1547. In all cases sometimes it helps to reseat the memory and remove all the battery and ac adapter to perform a powerdrain.

Hey! First of all, here is the cellular antenna: https://de.ifixit.com/Anleitung/Image/me... It sits directly above the WLAN/Bluetooth-Antenna. I also replaced the housing about one year ago and did not noticed any issues with the cellular connection. But I also can imagine a bad-quality housing COULD cause it. If you are sure the cables are connected correctly and have no option to test another cellular antenna I would try to use your old housing to test if it works fine there. Yes, it is a LOT of ugly work to but all back, but finally you can find out if the issue is the housing or the phone.

Good day! I think you should perform some further basic troubleshooting: - Try to use the old battery and check if the issue is gone then - Although you didn't touched the LCD connectors during the battery replacement please remove all of them and reseat the connectors to the board

Well, because of that you noticed there could be two options: 1st: Your fan is defect In my opinion the most logical idea regarding your observations, especially after the buzzing is not present the whole time and got worse if you stream something (= the system is more under pressure which causes a faster fan speed). If the fan is going to die mostly the system gets hotter due to the missing cooling and has no option to cool it down - this ends up in a slower system and finally freezing / sudden shut downs. In this case you also should notice a clear heat up of your system overall. 2nd: Your HDD is defect Also the HDD could make that sound, but - if the system runs fairly normally under less load - I don't think it's the issue here. A defect HDD is shown in a overall slow system, sudden and sporadic freezes or finally no boot (HDD not detected).

It is possible Chrome was deactivated at your Windows Sound-Manager. Go to the task bar (mostly at the right side of the bottom), right click on the Sound-Icon, open the the option "Volume Mixer" and check if Chrome is muted there.

It looks like a defect screen, especially due to the vertical lines. In most cases if the board really was damaged the touch or screen isn't working completely, but not sporadically only. This sounds more like a typical issue of a bad manufactured and cheap replacement screen. Try to reseat the cable, double-check if they are sitting correctly and try again. If it is still failing you should return it as defect and ask for a new one.

Does the charging LED lights up if you connect your AC adapter to the tablet? And does it shows any reactions after you plugged in the adapter?