Is a store liable for personal injuries sustained in accident due to store's negligence

Yes, the store could be liable. Store owners have a duty to keep their premises reasonable safe and free from dangerous defects. Given the fact that there was prior notice from an earlier incident, you could argue that the store should have known that its glass wall was a hazard. You should consult an attorney.

The store could be liable for your mother's injuries. I recently handled a claim involving an elderly woman who walked into a glass wall adjacent to the front doors of a sporting facility. The claim was settled for money damages prior to trial. In Connecticut, every person or entity in control of property owes a business invitee, such as your mother a legal duty to use reasonable care to inspect and maintain the property and to make it reasonably safe, a duty to warn or guard visitors from being injured by reason of any defects that the visitor could not reasonably be expected to discovery and the duty to conduct activites on the property in such a way as so as to not injure the visitor. The fact that another person was apparently injured in the same way prior to your mother's accident increases the likelihood that the store would be found negligent in your mother's case. Your mother should consult an attorney about the incident and her possible claims against the store.

Based on the facts, as stated, I believe that you may have a claim against the store. Please, contact a local attorney.