I have the new BDO app and had no issues opening it. Occasionally there's a glitch and a OTP text doesn't arrive, or takes longer than normal. I had one occasion with the old app when no messages arrived for a day, but next day was OK. Have you tried going into your branch and see if they can assist - you can 'live demo' the problem? They may well have a hotline number they can connect you to to fix the issue.
Incidentally, after some issues with the new app, I find it much better than the old one. I was on the verge of changing banks initially, but now use it for water, electricity, school fees, internet, mobile phone loads and GCash payments. All can be saved as favourites, which makes the process far easier. No more than two minutes per transaction.
Good luck.