[1] Looking at the disc from the underside, assure that the post on the bottom of the discs is aligned with the two pegs on the cap. Having the cap turned to the "off" position is helpful.
[2] Grip your thumb under the scalloped edge of the battery cap and pry the cap off with your thumb.
[3] Peel the cap off and set it aside exposing the inside of the battery compartment.
[4] The batteries will be nested in the battery holder with the [+] positive sides up on both batteries. The battery holder tabs fit symmetrically in the sidewall of the battery compartment. The battery holder needs to be placed inside the battery compartment with the exposed edge of the battery facing the exposed end of the LED lead bent over the sidewall of the battery compartment.
[5] The battery holder holds two CR2016 lithium coin cell batteries stacked. The exposed edge of the [+] positive side of the battery faces the LED lead and post.
[6] Pull the battery holder out and replace the batteries with two CR2016 lithium coin cell batteries. Be sure to place them back in the battery holder the same way they came out.
[7] Pull the battery holder out and replace the batteries with two CR2016 lithium coin cell batteries. Be sure to place them back in the battery holder the same way they came out.
[8] When putting the batteries back into the battery holder, set the bottom battery in first so that the positive side is under the battery overlap. This allows the top battery to cover the flat edge of the battery holder.
[9] Snap the top battery in the battery holder.
[10] Snap the top battery in the battery holder.
[11] Place the battery holder back in the battery compartment with the exposed edge of the top battery facing the LED lead and external post.
[12] Press the battery holder back in the battery compartment with the exposed edge of the top battery facing the LED lead and external post and the battery holder tabs secure in the compartment channels.
[13] This is a repetitive picture of how the battery holder fits and aligns the top battery with the LED lead.
[14] Nearing completion here; place the battery cap back on top of the compartment and align the cap pegs with the post. Assure the cap is going to fit back in the "off" position.
[15] On a flat surface snap the battery cap down flat on the battery compartment. The cap should be able to twist to the on position illuminating the disc.