10-11-2018 04:56 AM
Motherboard replaced. Board was bought from ebay and did not require me to enter Windows authentication. Hard drive was able to boot windows after the motherboard replaced.
Now I can enter bios and it displays Lenovo serial number invalid after the motherboard replacement.
BIOS can be accessed even with internal motherboard battery removed(CMOS) I have done this as a test since I did not know the implications.( CMOS battery and Main battery removed including AC power. System powered with only main battery installed, computer started as normal and system time was not affected)
I sincerely thank everyone who have participated and commented. Hope this process can be of help to others!