Yes, actually, you can still determine the keys. The usual method is to scan the rows and/or columns one by one and then you always only have one row and column

Yes, actually, you can still determine the keys. The usual method is to scan the rows and/or columns one by one and then you always only have one row and column active at a time, so you can determine individual keys. However, if you strobe too slow you can miss keystrokes.