Can you connect to the UNIX Operating system of this HANA system using the SAPSID and execute the below query to understand if the required services are running for HANA
sapcontrol -nr XX -function GetSystemInstanceList
(replace XX with INSTANCE number)
If you do not find all SAP HANA Services running and showing GREEN then try a stop and start of the services
sapcontrol -nr XX -function StopSystem HDB
Start the system:
sapcontrol -nr XX -function StartSytem HDB
(replace XX with INSTANCE number in all queries)