Hi,
There is a problem with site password. Uninstall server tools and delete old password and restart the system and install server tool again.
Note your new password and enter correctly in site password. Already I have solved this way for one of this forum member. I don't know exact thread attach here.
Also refer SAP note for workaround ( neglect language problem and follow the steps for new password).
1905731 - Turkish password cannot be used for B1SiteUser
Thanks & Regards,
Nagarajan