I bought a OEM battery for my tecra and now the laptop freezes during boot (the screen stays black with an underscore blinking) with the battery plugged in.
In most cases the blinking underscore is related to faulty HDD or RAM issue.
In my case the HDD was faulty and therefore I got similar notebook symptom.
I’m not quite sure where the connection between blinking underscore and the new battery is but the whole computer world is really strange sometimes and many strange things can happen… so maybe the new battery is faulty…
Did you notice this issue with the old battery?
If not, then I would recommend testing other battery… maybe it helps…