Wedge a thin piece of wood shim in between the retracted guard and the metal housing that will easily keep it up out the way.
When I bought my 10" Ryboi chop used saw may years ago I first thought the retractable guard was broke in some way but the previous owner had done just that with a piece of wood. I guess he didn't want the guard in the way when he was cutting
As for the blade lock have you rotated the blade around while depressing the pin? Usually that's all it takes to engage the spindle lock on most saws.