@nick @oldturkey03 The OEM adapter arrived today and I just replaced the new power adapter, the issue goes away immediately. The monitor can boot up immediately without waiting. The syndrome is very similar like the video below, it has a very soft hissing sound coming from the monitor when using the old adapter, the monitor will power up and flash once. After replace with a new adapter, the hissing sound also gone. The OEM adapter only cost around $4 USD. I save myself 100+ bucks without a need to buy a new monitor. Thank you so much for the feedback and help!

https://www.youtube.com/watch?v=Kwwi06GG...

You need to open the system, check if the power supply is a foxlink. Foxlink power supplies have a bad solder job and you need to resolder the power plug so it will work again. (Reason being is because you have stated that the cord has been replaced, so therefore internal issue)

To Open the Xbox console, you will need a couple of special tools. You will need a TORX T-10 screwdriver and a Torx T-20 screwdriver. The XBOX case has 6 T-20 screws and to remove the hard drive and DVD drive, you will need to remove 3 torx T-10 screws. The power supply is held down by 2 torx T-10 screws.

http://www.llamma.com/xbox/Repairs/power...

The link above explains how to fix the issue.

If this has helped please vote the answer and accept it. Many thanks and all the best