Always need to 'option' to select boot device

I have an original 2008 MBA with a completely dead battery - if I kill the power it instantly shuts down with extreme prejudice. A while ago I replaced the HD with a Runcore SSD, which has been faultless.

Now since the battery finally died a few weeks back, we've had a few powercuts and of course the MBA dies instantly when the power goes off. Since that started, it now won't boot back up again without holding OPTION to select the boot device. Even if I correctly reboot the MBA from OSX I have to OPTION at boot.

The SSD checks out ok in DiskDoctor, and the boot device is correctly selected in Settings.

Any clues what could be the problem?

Weaselboy said:

The boot drive settings are stored in the pram and I believe since you have no power to the device it is losing those settings each time you power off. I don't know of a fix or work around.

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That's it. Didn't think of that. Simple - thanks!