The battery may be depleted - replace battery. The battery may not be installed correctly - please see user manual for installation instructions. The battery may not have proper connection with the contacts - clean contact surfaces and reinstall battery. Battery cap may be loose - tighten the cap and try again.
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All Aimpoint® sight are shipped “factory-centered” from our manufacturing facility in Sweden. Normally this means that only minor adjustments are necessary, providing that the weapon rail is properly aligned. Do not continue to adjust windage and elevation mechanisms on your sight if you encounter resistance; instead check alignment of the rail (or carry handle) to the barrel. If the impact point is moving, check the hardware on the mount and the weapon rail (or carry handle). If you still cannot zero your sight, call Aimpoint Customer Service for assistance.

If the dot does not appear to be perfectly round, this is probably caused by the way that your eye perceives the dot, rather than by any mechanical defect. Due to differences in individual eyes, round objects may appear in a variety of shapes. A simple test that can be easily performed allowing you to determine the cause of the perceived variation: (This test is easiest when the sight is not mounted on the firearm but can be performed with the sight mounted as well. Just make sure that the firearm is unloaded and pointed in a safe direction.)

• Turn the sight on and look through the sight.
• While continuing to look through the sight, rotate the sight on its optical axis.
• If the irregularities seem to revolve around the center of the dot like the spokes of a wheel, there is a mechanical defect causing the distortion.
• If the dot irregularity does not roll with the sight, the variation is caused by the way your eye perceives the dot. This is not to say that you do not have good vision. You can see clearly and still perceive an anomaly in objects this small. You can also try taking a photo of the dot with a cell phone or digital camera

This is normal for all Aimpoint® Micro series sight. The power intensity adjustment control moves when tightening the battery cap. When tightening the battery cap use the Aimpoint® Micro Tool to firmly turn until resistance is encountered. Then continue to turn until the battery cap comes to a stop.
See our how to tighten the battery cap on Micro series sights here...