“Clearly all is not right”. Yes, they did not want you working for them any longer. You did the right thing by not resigning. Surprised you got a severance check, that is unusual. If you resign, you probably would not be eligible for unemployment. Unless they fired you for cause, you are eligible. So go and apply for unemployment, then start looking for a new job.
Termination of an employment cannot be done without proper notice period. If at all the Org wanted to do termination, if at all you have committed any loss to the org in your allocated tasks or escalation from client or poor performance, they must be serving at least 3 notices seeking your explanation. Upon dissatisfaction of your explanation only with proper reason they can go for immediate termination. Now in your scenario you can approach labor court for justice and the org will be penalized for their illegal approach.
Bro, organisations can come up with N number of reason with makeup proof if they have made mind to terminate you. In no way you can escape or do anything. I have seen many such helpless Indian employees. They cannot fight with companies and finally have to put down paper instead of going for termination. In termination, it will be difficult or nearly impossible to get next job, so employees resign to show to other companies that they have resigned voluntarily. That is why HR and Manager in Indian companies keep on threatening employees. Indian states has no strong labour law compared to USA and other countries. So just forget if you are working in India and for Indian IT. Before voting to your so called illeterate theif Indian politicians ask them to form USA like labor laws. In india the govt is always on company management side and not on employees side because these parties gets huge funds from these companies to cater their election rallies, so that they can get favor from politicians and party and frame policy which helps the company not the employees. I hope you got what I’m trying to convey.