Cost of repairing electrical main panel

[Aiko Klein]

My family owns a condominium in California. The history is that there was serious electrical arching in our unit starting about a year ago. We had an electrician check the inside of the unit and the problem was at the main electrical panel in the garage. We've been going back and forth with the HOA arguing about who will pay for the repairs. Finally last week, without agreement, the HOA proceeded to hire an electrician and repair the main panel. Now they are asking us to pay for the full cost for the repairs.

What is confusing is that the main panel was faulty(broke from normal wear and tear) but it affects only our unit. We feel that since it's the main panel the HOA should cover the cost. HOA says we should cover the cost because it affects only our unit. At this point it is a grey area so we are planning on proposing to pay for half of the cost and they incur the other half. Any thoughts on how to handle this situation?