Old Wrench Imp - New blink-up app

I have a NIB developer edition imp (the creature is holding a wrench)

Should the current blink-up app work?

On iOS, yes. On Android, probably not. The blinkup scheme was improved significantly in ~2014.

If you have an android, try enabling “legacy mode” (tickbox at the bottom of the screen) - but if all else fails, borrow an iOS device to get the imp online so it can upgrade - it’ll do that at first connect, then you’ll be able to use Android just fine from that point onwards.