Drilling holes in a sealed lead acid car battery - 080

I have a 12 volt car battery 100AH. There are many indications that it has a bad cell.
But because it is a maintenance-free battery, it is not possible to enter and measure. Therefore, I must drill holes in the plastic and sure enough, it has a bad cell!!
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My PlayHouse is a channel where i will show, what i am working on. I have this house, it is 168 Square Meters / 1808.3ft² and it is full, of half-finished projects.
I love working with heating, insulation, green power, alternative energy, solar, wind and more. It all costs, but I'm trying to get the most out of my money, and my time.