Just read your poll, (The battery on you computer ran out/ no replacement/ do you) and all the answers you suggest in my opinion are incorrect. The correct answer is: convert your dive to tables, and cotinue using tabels and annalog gauges/timer. I always dive with a back up.
re-quite liked diving out of brockville in aug/sept when the river is toasty warm!
Yes the St Lawrence is nice in the summer, no thermocline, & about 21° C is not hard to take. The wrecks are great too. I lived in Brockville for 20 years, met & married my wife there.
Middle east & Carribean diving wow. Must have been a adjustment to the cold Canuk waters, Ill bet. I hope to get to the Red Sea soem day, I'll have to get in touch when things settle down over there. Too much sabre rattling with Iran & Israel right now , for my liking.
re - your poll, dive computer dead battery. I couldn't answer, by selection your choices.
My answer is : switch to anolog gauges (my computer is hose integrated (cobra)), convert last dive to tables and dive with back up tables & watch. ( I keep analog console on my Save-a-dive kit)