Testing PayPal standard payments on live site after Woocommerce updatea

Hello, I’ve just had a call from an irate client that the PayPal standard payments have stopped working on their website resulting in a los of a lot of money today.

After checking on here and his website I found a new Woocommerce update from a few hours ago and the looks like it has fixed things but how do I test it for sure on a live website? I can’t take it down long enough to turn sandbox on to test that way. I went through checkout all the way through to clicking on the PayPal pay button and cancelling payment from within there but not 100% sure that it is ok.

what do others do in situations like this?

Best regards,
Angela