Unfortunately, in this case, the control on accessing the laptop is no longer on your Microsoft account, but on a BitLocker key that must have been stored on your Microsoft account, or on a USB drive.
Since you do not have the key, it will be impossible to access your laptop now even though the MS account is now accessible since the computer now requires the key.
This key was triggered due to several failed login attempts.
The only way to regain access to the laptop is by perform a factory reset. But please be warned, factory reset wipes all your data on the drive and then reinstall a fresh copy of Windows 10.
If you have a lot of personal files on the locked laptop, please have it recovered by some local techs there before performing the factory reset.
Here is the link about getting locked by BitLocker:
I know this is not the kind of answer that you wish to hear and I hate to be the bearer of this bad news. But it will be unprofessional of me and unfair to you if I will not give you the real state of your scenario.
At this point you placed a deposit and it is up to you if you want to give me credit for assisting you or not. Your deposit is refundable should you wish not to pay. But please do not rate me negatively (1 to 2 stars) as I have done everything to assist you and that the situation is no longer on our control.
Here is the link about refunding:
Thank you for using our service. If you need anything else, please let me know. I am still here to help.