HP Pavillion DV2000 Laptop "HP Pavillion Entertainment PC" Motherboard fault

Dear Forum Members,

I have a HP Pavillion DV2000 Laptop "HP Pavillion Entertainment PC" with the following specifications displayed on BIOS:

HP Pavilion DV2000 (RG414UA#ABA)
System Board ID: 30B5
Processor: AMD Turion (tm) 64 x2
Processor Speed: 1600 Mhz
Total Memory: 2048 mb
Bios Version: F.39
Serial Number: xxxxxxxxx
UUID Number: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

and a label on the back of the laptop:
Product: HP Pavilion DV2000
s/n: 2CE70512R6
p/n: GA726EA#ABV


The laptop had the following faults:

1. When you switch it on will most of the time will be on with a blank screen until you switch it on and off twice or thrice.
2. It will either load windows Os normally or show no operating system found.
3. Faulty AC adapter Model: PA-1900-36 OUTPUT: 19V-4.7A, INPUT: 100-240V, 50-60Hz, 2.0A

Steps done attempting to repair the laptop:

1. Used another HDD but still the same fault appears "either load windows Os normally or show no operating system found"
2. Took off the HDD and used it on another laptop and worked perfectly.
3. Disassembled the laptop and found the motherboard part to be SHIBA Motherboard 05234-3 484F701.031. Having no motherboard parts in my country i assembled back the laptop and was taken abroad (Country withheld) for motherboard replacement.

The laptop came back with the same above faults. Though i was told it has been repaired. Before i press charges i wanted to share this with forum members for advice.

1. On BIOS Setup i see the same specifications such as same serial number, UUID Number.
2. A replacement AC adapter Model: PA-2521U-2AC3 INPUT: 100-240V, 50-60Hz, 1.5A OUTPUT: 18.5V-3.5A, Instead of an AC adapter of the equivalent rating.

My Questions:

1. Does the serial number and UUID number remain the same or changes with every motherboard replacement?.
2. Does the replacement AC Adapter Model: PA-2521U-2AC3 INPUT: 100-240V, 50-60Hz, 1.5A OUTPUT: 18.5V-3.5A safe to be used by laptop instead of AC adapter Model: PA-1900-36 OUTPUT: 19V-4.7A, INPUT: 100-240V, 50-60Hz, 2.0A?.

Your assistance is highly appreciated.