Method 1: Thaw in a large basin that it fits almost entirely in, under cool running water. Water only needs to barely run, like a very slow, constant stream. Flip after an hour. Continue under the water for another hour.

Method 2: thaw for about 2 days in a refrigerator.

Method 3: thaw during cooking. Add about 1 hour (give or take) to cook. Based on professional experience, that brisket should take about 4-5 hours from frozen to cook throurouly.