Regarding unauthorised absence

I am working as SDE in BSNL.In 2019 i was working as JTO in BSNL in Ambala .I visited USA while i was on maternity leave till mar 19 and noc for going abroad was given by my department till mar 19.I extend my leave with CCL till Oct 2020 while staying in USA and address during leave was given as USA address and same was approved by leave sanctioning authority.During the month of Sept i got transferred to faridabad while I was on leave.Due to COVID i was not able to travel back so i asked to extend my leave,which was rejected.Due to travel restrictions/ban i did not joined for 8 months and was communicating same to my office in faridabad via letters.I also submitted medical certificate from USA doctor to my office.I joined my duty in faridabad on July 2021 and i was promoted to SDE. Now following questions i want to ask (A) My general manager has asked to take disciplinary action against me and they are planning to give me minor charge sheet. because of (1) expiry of NOC (2)unauthorized absence from Nov 2020 to June 2021 As the situation because of covid was not in my favor and also i always mentioned address during leave as USA and same is mentioned to my controlling verbally in telephonic conversation.still i can get minor charge sheet how can i save myself from that. (B) Also i want to apply for study leave for studying MBA in USA .can i apply for the same as the course will start in Nov 2021. Can my application for study leave be rejected.