<p>Some program froze my calculator. I tried taking the batteries out, and is still frozen. All I have is a screen that says illegal instruction. Any suggestions what to do?</p>
<p>yep it happened to me. You have to take out the watch battery that is under the screw cover (and put it back in of course).</p>
<p>hold left + right + 2nd + on all together</p>